Ranked Players against high rating players

I have been checking out stuff on chess.com and i have noticed that there are plenty of players who are ranked in the world on the site, and there are also a lot of players who are not ranked in the world or there profile doesn't label them as a GM or something of that sort.  I guess my question is how do these high rating players compare to the GM's on the site and/or why are the high rating players not some type of ranked master themselves.

First, maybe they don't want to tell who they are. Second, maybe they play against weaker opponents than they should (which you can't do in rated tournaments) If somebody rated 2400 plays only against player rated 1700-2000, his rating obiviously grows, since he/she don't play against opponents who is as strong as she/he is.

I think its due in part to the fact that turned based chess is a great equalizer, as master's opening knowledge and extra tactical skills can be over come easier in this style then OTB one. I mean we can use data bases on masters games and we can use opening books so masters dont always have it there own way quite so much. and we can use the analysis board to calculate variations with, so making less mistakes then u would over the board in tournament games...

I think the top rated players who aren't titled must have played some pretty high-level chess at some point in their lives - strong tournament players, I'd have thought.