People wanted T0 garrison counter, lots of good players did
I am assuming you are referring to team games because although garrisons are frustrating they are by no means op in 1v1. If you are reffering to mg spam or mgs rushing to key buildings thats different.
The thing is, the usf morter is not op vs buildings. IME a building and the unit inside can take indirect fire for a considerable amount of time. The counter to garrisons has always been flamers.
However, by trying to fix 1 problem in the game they have inadvertently broken other areas of the game and weakened the overall game. The usf morter is op vs non garrisoned and especially vs units bunched up in cover. I have always thought that indirect fire tends to remove positional play from the game because you will get wiped or at least loose enough squad members to be at risk of being wiped. So the game has devolved into bumrushing your opponent and trying to force a retreat.
The other problem is by giving usf a T0 morter it basically has all counters necessary to counter axis openings and thus another decision is removed from the game making it weaker overall. Some people will argue that each factions should have all tools available to counter opponent and the game should be decided entirely by micro and positioning. That to me seems like weak design because decisions are based entirely around which unit to build and less about teching and overall strategy.
Disclaimer : I am currently only playing usf and have been since brits bullshit began.