They might not quit if there was actually people to play with. I think reason people don't help anyone is because they want to charge them for it. Most cliques are 1 or 2 people now a days running multiple characters. Also the game is old and noone wants to do old content again and the people still playing are just die hards who refuse to move on.
Or maybe they are having fun still and enjoy it? You sound really disgruntled. I dont get why people still don't understand this is a video game and people play it to have fun and enjoy themselves. There are people to play with on every server, you have to try and make friends. It's been like that since the beginning. Yeah most cliques are people multi boxing but you don't need more than 6 for anything in the game now. So you can find one or two people, who most likely multi box, and do everything and anything.
Blame SE for how they treated this game over the years, don't hate on the people who still enjoy the game. Its a sad fact but helping new or returning players, ya gonna get burned. I make sure I at least benefit somehow. Not gonna help if I'm not having fun or benefiting.