Not standing on a soap box, but from experience, All are valid reasons provided of cource you are looking for a relationship that has some meaningful connection. But all these answers have a common theme, all problems exist outside the user.
What is the users motivation for the relationship? Is it out of self improvement? Maybe they have something to offer another that is of value. Maybe you have extra in so many areas you are compelled to put that Love into the universe.
Too many times people put the internet and other uncontrollable circumstances to blame for the reason why they can't make a relationship work whether it's online or offline. what about billions of socially conscious people all doing their part? in the end the love you take is equal to the love you make... I think one of the Beatles said it I'm not sure I'll have to check with my wife.
just go online and make friends chances are you might make a connection. If it works out, it works out, if it doesn't, it doesn't, but it's not because billions of horny people need sexual release and to experiment with their sexuality, or because there a hater and they just want to be a d**k.