Except the only reason people use steam is because they bought HL2 and were forced into it. Then years later when other games appeared they decided "aw fuck it" and bought them. Now steam community has grown, but in reality like 70% of it's users were HL2 customers.
Xbox live wasn't chosen either, many people use it because they own a 360. No doubt some bought it because of it's online experience, but it's not like you can choose something else.
So anyway my point is it can't rival something that wasn't a choice. I can NEVER give up steam because it would mean I can't play HL2 or any other games I purchased over it. People can't give up Xbox live because then Halo 3 and etc can't be played online.