What's wrong with being older than 20 and playing the game? Just because it says it's for a younger audience, doesn't mean it's wrong to play it when you're older. I'll tell you right now that I'm 21, and I still find enjoyment in the game. I don't find it sad. I have a job, I go to school and I have fun talking with friends on here. Just like ZepeuS said:
If this is the way people want to spend their lives, let them. If you don't like it, don't bother yourself with it. Talking bad about people who are still playing this game at a certain age is rude (as well as the dating). There's no need for it.