3. i don't really get what you are saying there. but even if all players go for t3 or t4 and get non-doc tanks, because of a huge amount of caches usually involved with 3v3+, unless the players are bleeding tanks left and right, doctrinal choices for tanks, t34/85, is2, special sherman, tiger, and some more eclipse the effectiveness of non doc tanks pretty easily.
I agree with you, that doctrinal tanks are better than non-doctrinal tanks. But I don't believe that is a problem, because why would you want to pick a doctrine that works as a downgrade? Hence I believe the problem lies purely with call-in spam, not with call-ins being better than non-doc tanks.
Furthering your point about the fuel caches in 3v3,4v4; This is why waiting for Call-ins is less effective. High fuel income means that you will have enough fuel for tanks before you hit 10-11 CPs. waiting 3-4 CPs while your opponents run around with 5+ medium tanks, I believe is highly dangerous