I'd be fine with Relic and the top players doing all the testing as long don't go too far down the rabbit hole. They've bordered on that with USF, making a army that can be OP if micro'd really well but is just a bunch of fragile units if not. Then the elite players complain about it because USF wins most of their matchups while the general player base complains about it being UP because they can't micro like Jove (or pick name of any elite player). Also, units that are good only if micro'd well in 1v1 or 2v2 usually don't scale well in a 4v4.
TBH, the top players in this game really don't have great control compared to the top players in other games. The engine is too unstable; and movement/pathfinding is too unpredictable.
As for factions being balanced only if you have good micro: what's wrong with that? If lower players can't compete just have somewhat competitive commanders that are less punishing for player with low APM. Bad players in a game like Starcraft can't micro like the pros but you can still reach the top of the ladders by learning basic timings and builds alone. RTS have a lot of dimensions.
And having high-micro units that don't scale into 2v2 and beyond seems like a good thing for relic. It will make it easier to balance the format most players engage in (team multiplayer) versus the competitive format fewer players engage in (1v1 laddering).
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Biggest fault of the patch is of course the bullpudding AEC car being so OP. It's always been a problem with British design. They are too campy by nature which makes them hard to balance because if there are mobile units are too strong, then their emplacements push them over the top. AEC spam into camping on the opponent's side of the base is basically auto-win for british right now.
Fundamentally they need to change british from being so campy and more versatile like the other factions where there are commanders that are more mobile and offensive. The camp design should've been discarded after OF anyways. It's not fun at all to play against or watch in 1v1 and creates static, boring games. Just leave that aspect to big team games where balance doesn't matter as much anyways.