It is possible that the people who are playing 21 points are not as good. At least in this part of the world, most of the people who are playing to 21 are lower level players, often they don't know that the rules have changed, and the people who play to 11 are usually people who play at a higher level and know the game better.
I may agree that they are might be not good enough playing, but i disagree that they don't know about the new rules or changes, maybe they play with 21 sets to give more people chances to play, mostly with 11 points sets they have to get minimum best of 3, and that may end up with 2-1 which is really long for many players to wait for few tables there, while with 21 set it is like playing 2 sets of 11 in one game, or even 3 if they goes until nearly 20-20, but they do play another places where they apply the rules, i did play against one european man who seems very good at playing, he is not young man, and sounds he sure knows about the new rules or changes, but he accepted to play with 21 as i did, and he was very nearly to beat me but i managed to win.
Actually, i played against some students too in that university about 1 month or little more ago, and i played with 11 points games, and i managed to defeat them all with luck, i always lead first game and win the third if it is be of 3, even when i lose most of the time i take the first set with many opponents i played against, i am talking about those are are nearly my level more or less, i have no match to those higher levels even if i played 21 games not 21 points.
But, i am with all, i also see that 11 points is better than 21, i just wouldn't mind if someone would like to play 21 points with me, i am a flexible player with rules.