The whole point of the discussion is about courtesy. Now, it looks to me like some of those who are claiming here the unacceptability of not resigning are doing so with a bit of lack of courtesy :)
Let's be courteous both to the skilled players who need not to waste time, and to the beginners who play how they feel is appropriate. Let's be courteous both to those who think that resigning from a lost postition is a must, and to those who don't take offence if the opponent has a different view of whether or not to continue their game. I've read far too much aggressive language here (from some), for a discussion on courtesy.
I think a 1600 with 'years of experience' should have a higher rating. Either the work is not being done, or not being done correctly. If a 1600 worked on one and two move tactics until he or she could spot them right away, even seeing if the patterns are possible a few moves away, that player would hit 1900 or 2000 at the very least. And this should only take less than an hour a day for not very long.
Tell that to poor Ziryab then, who still isn't above 1900 even with his age and experience.
In OTB chess (which is much different than online chess), the rate of increase in your rating really depends on when you start. In the USCF it really can take several years for a young, beginning player to advance up to 1600+, unless they are just obsessive with the game or the area in which they live is a chess hotspot with tournaments and great players galore.
The rate of rating increase can also slow down depending on how much free time you can actually devote to tournaments. Not everyone can go tournament roadtripping every weekend you know (especially me, what with college and all, and especially family men).
=Edit=
Also, just thinking about it a bit more, it also depends on your competition as well. I found that raising my rating in the state scholastic events was very difficult, because even if you won a lot of games, there just weren't that many high rated scholastic players around to give the nice rating boosts. In the elementary divisions it seemed as if 90% or more of the players fell within the 1000-1400 range.