Well that sounds like there is no better way than constant overturning and then nerfing things into obscurity. I mean I get that a game with so many factions is hard to balance. But going for "welp that's just the way it is, things will never change" is letting GW off to easy for doing a not so good job imho. You have the same issues in 40k and they seem not to learn at all. Also the reflex of immediately acting and rushing out nerfs is not giving enough space for the players to maybe develop strategies first. If I look at competitive RTS like Starcraft for example there were often strategies or units that appeared imbalanced for a long time. But instead of instantly reacting to every cry from the community Blizzard (the good old Blizz, not the current mess) let the game run for a while. And suddenly those unstoppable strategies found counters. It just needed time and pressure. People will never go out and try all kinds of crazy ways to win against an apparently overpowered opponent if they are used to just crying long enough and then getting the nerfs they want.
I admit of course that there are some issues that need fixing, in every game. But just a couple of months and the data of - how many, a couple hundred? - games is not enough time at all to evaluate the situation. So, honestly, I can't help but think that there is also a sales component to all that.
"Oh you bought some new models because they were useful? Well we nerfed them so you will never play them but thanks for buying. Anyways we made THESE new models (or old models you never bought because they sucked) that now are really good. Would you mind buying them too, before we make them unplayable?"