I can't speak on high level games but from my time here, the tank Foundry's units are very expensive and every tank is massive reclaim, the tanks get the Kodachi which is their only early game tool to threaten their opponents, its not so OP because at a certain point they end up hurting each other more than anything, mass blitz is kind of weak, even if they do have that high hp pool for a raider, I would go mass minos instead.
switching INTO tanks is something I see often so if they're THAT strong and EVERYONE switches into Tanks then we can have a conversation, I just don't see how a few racketeers or a lance for sniping low hp units couldn't work, hecc you can sick a bunch of darts at them too
If they're ahead and there's that many Tanks on the field, I don't think the Tanks were the problem
But again, I can't comment on high level play and the meta and all that, just my two cents.