I think I know why they do this but it still bothers me.....why is it that on most SG's main pages you cannot request a friendship? That really fucking bothers me. I have a few that are my favorites and just think this is strange, probably warranted, but still bothers me. 
b) Some want to keep their friendships to a certain number.
c) Others simply don't want to know people they never met in real life.