Re: Spot on
"The only thing people value is other people they want to talk to are on the same network"
I'm not convinced, nor am I convinced that people on Gmail prefer their friends to also use Gmail. People want to do social things - it's the things they do, and the people they do it with, that they care about. Services, not providers
I don't know, or care, what phone network my friends are on (or myself, without opening my phone and checking) - I can just call them, and interact the same whether they're on my network or not. If that was true for Facebook and Twitter (spoiler alert - it isn't) then people might talk about how their social or microblogging PROVIDER was better, but since they're talking to you on the same SERVICE, they (probably) won't be urging you to switch.
Incidentally, I much prefer Google+ to Facebook. It's so peaceful over here...