I think you care too much about your meaningless online rating....
multiple profiles on the one account?

Wow thanks for the really insightful comment, that was great, you really contributed something and made an effort to understand where I was coming from, cheers!

I'd say there's more against it than for it. Yes, it'd be nice, but the reasons you list for not allowing it greatly outweigh the positives imho. With an elementary proxy server you could even run two accounts from the same computer and be undetectable. If you want to try experimental play there are plenty of other free sites.

Cool, thanks but I didn't really list any negatives. If you weren't allowed to play one vs the other etc. then it's not a problem, could you elaborate on what you thought the downsides were?

Well, there's Live Chess...
A couple of times I wanted to try some new tactics I'd recently learnt, I went there and played a short game or two.
Or, as you said, you could play unrated. I personally don't care much about my rating, so I seldom play unrated, even when trying new things. I don't know how much an online rating is truly related to any official rating.
And I never use the analysis board or a book of openings, when playing. I like to think that that way I am developing my ability to calculate. My brain gets used to "seeing" several moves ahead without actually seeing.
If you care that much for your rating (I can tell it's pretty high), but you still want to try new things or crazy ideas, you have two options:
#1: Play against a user with a much lower rating. That way, even if you play weird, they probably won't be able to capitalize on your weakness anyway. This option has one disadvantage, though: If your opponent beats you, your rating will go down like a brick on the water, so to speak.
or,
#2: Play against a user with a much higher rating. This one has two advantages: First, if you lose, your rating won't go down as much. Second, --and perhaps the most important-- your opponent will most surely take advantage of the weaknesses of your position. If you study the game afterwards, you will see what went wrong, and perfect your new tactics/strategy.
Once again, if it's all about playing in a more relaxed way, not caring for proper tactics or any sort of analysis, you can always play unrated.
Regards,

well say you had one profile where you used analysis and opening books and one without it'd be interesting to see how your ratings ended up in comparison.

well say you had one profile where you used analysis and opening books and one without it'd be interesting to see how your ratings ended up in comparison.
you could use live chess!
Use the analysis and book openings for turn-base and don't use them for live chess.
That's what I do...and my live chess is like 200+ points lower~

Cool, thanks but I didn't really list any negatives. If you weren't allowed to play one vs the other etc. then it's not a problem, could you elaborate on what you thought the downsides were?
You're right, you didn't. You said "Obviously you couldn't play one profile against another or join the same tournament or anything like that." With multiple profiles for the same account those things would be detectable, mea culpa. I should have read your post more carefully. However, I can still see a downside - if you had a 2000 profile and a 1300 profile your opponents would not have a fair idea of your real strength when challenging your lower rated profile.

Yeah this is a good point although anytime a good player joins they'll cream alot of unsuspecting people for a while. After a bit any rating should stabilise at some kind of meaningful point.

Well, I was speaking of fast Live Chess games. Maybe 5 min, or so.
But that's me. :)
White Knight is right there, and even with just one profile, you never know what's the real strength of your opponent. Perhaps their rating is too low due to having played many experimental games, or too high from having used a chess engine.
That's the thing with ratings, especially with online rating. You never know...

I don't like it. If you asked me why, I couldn't explain except to say it seems wrong.
+1

If you want to play more experimentally, just play bums like me. Your superior knowledge of tactics should win the game for you.

I don't like it. I don't see the reason to allow a player to have different profile for different (self-imposed) playing types. The split between live, blitz, bullet and online (and chess960) is clearly defined in the system and by different chess organizations.
If you want to preserve your high rating then continue playing the way you do. It doesn't mean much anyways, since ratings are relative to the pool. And our pool's shallow end is very shallow...

Well I think the point here is that in playing different styles the rating becomes useless. A lot of people here say a rating is meaningless; that might be true, but it is very useful if it were to tell you the strenght of your opponent. That is, if this opponent uses his same style of playing!
Playing Oort at a rating of 2000+ knowing that he is using books and other allowed assistance (as I do myself also) will be a lot different from playing him when he doesn't.
Him playing different styles all the time will make his rating go up and down a lot. One does not know what strenght to expect. Might be he was just on a low starting to play his better chess, you'd lose and lose a lot of points along the way.
Another point here is that he might want to play high-rated opponents, thus he does not want to lose too many points because with a low rating it gets harder to find a high rated opponent or to get in a high rated tournament.
All this said, ratings in on-line chess are often conceiving. I've lost some games to players who turned out to be very good as there rating had just started. My own rating often gets too high because of stupid wins on time etc. etc.
As for the main question, why is it forbidden to have multiple accounts? How is one to find out? Can your relatives have an own account on your PC? Can you ask your nephew the grandmaster play a couple of moves for you? The fun is only to your self to play a fair game. As long as you can be true to yourself and your opponent I'd say, just go ahead.
edit: Playing unrated games will not tell Oort what he wants to know: how good am I without the books. As for that, I give TacticsTrainer more credit to where my rating really stands.

Provided you play consistently to your (alternative) personality, there shouldn't be too much of a problem. However, what happens when your risk-taking, free'n'easy clone gets a few rating points under his belt and start to think: "Blow this for a game of soldiers, I want to protect my rating". So he creates a new, anything goes clone - and everything goes smoothly for a while until Mk.3 get a few rating points, and then, before you know it ... Multiplicity!
For good reasons it is illegal to have more than one user account, however I was thinking that it might be good to be able to have more than one profile on my account. After having worked fairly hard to build a reasonably decent on line rating I'm a bit reluctant to risk it but I sometimes get the urge to play much more experimentally/attacking/differently to how I would usually play. It would be great to have a second profile to indulge these whims without ruining my current rating. I tend to use the analysis board and opening books from time to time and it would be great to have another profile dedicated to emulating OTB conditions as much as possible. I realise I could just play unrated games but it would be interesting to see how these things played out in the rated world. Obviously you couldn't play one profile against another or join the same tournament or anything like that. I'd like to know what other people think of this idea, any reasons why it wouldn't work or hopefully more reasons why it would be good...