solution:
stop playing 4v4, start playing 1v1
There are people out there who have friends and enjoy playing with them.
Add fuel/muni caches to the list. Fuel especially.
Realistically, a few caches built in the first 10 minutes inject around 1000 fuel total into the economy of a team over the course of a team game, which equates to around 7 medium tanks, or 3.5 heavy tanks, on the fuel cache alone.
This, too, can be solved without touching 1v1s. Make the caches only benefit the owner, not the team, like Opel Blitz.
Why should players who sacrifice alot of MP to contribute to the "war effort" be punished because their lazy teammate built a cache first? I'd rather reduce the amount of safe points to a minimum.
Most maps could need a reduction by 2-4 points. In fact, you can see that most of the 3v3+ maps have completely overthrown and ignored the competetive map design of 1v1 and 2v2 maps. Cut offs are almost non-existant, fuel points are either 100% safe (Lienne) or are both strongly contested (Steppes).
Your proposal is just unfair and would cause toxic behaviour. It doesn't sounds like it's been thought through.