can you explain how you "severely weaken" your team by doing this?
Sure Sir. If you are playing vs any decent players, they will exploit your lack of involvement in the game and double up on your teamate. Effectively wiping him of the map and also taking all the valuable resources in the meantime.
It doesn't matter how many Shermans he ends up spamming, because he will be fighting 1v4 by the time he spams enough Shermans.
It can only work vs noob players, but then again other teamates would be able to win that game without his Shermans anyway.
Stupid and pointless tactic
It's same thing as some noob guarding VP in the corner while his team is being doubled and pushed of the map. Yes he has a lot of units by the end and he will proclaim how he held his point, and his noob team lost the game. Yet he is the noob and reason game was lost
Same thing, someone who doesn't understand how this game works would do that