How would squad voice/text work?
There has to be some unique identifier on your account that tells the host what squad you're in. Today, it's your gameid. If you wanted that gameid to be in multiple squads, you'd have to come up with some other unique identifier that somebody would have to set when they log in...
Which leads to somebody making the wrong choice, ending up logging on as somebody else, then god-knows-what-drama ensues...
Sounds like a headache to me.