So is the complaint that there has to be a breakpoint in the system?
Because that's a simple matter of mechanical legibility. It provides a visible marker for "Does my unit have enough AT threat to keep the enemy tank formations honest", and vice versa.
Clean breakpoints mean that you have tangible goals to design around and metrics to check. The more sliding scales and blurriness you have, the harder it is to really see what's working out for you and what isn't. That way lies fatalistic apathy, because you might as well just throw shit together and hope for all the information you're getting. Clear information, on the other hand, lets you prepare. If you are fairly certain they'll have ~30 Armor, then you can budget for enough AT to get ~35 Piercing in your divisions (all numbers totally arbitrary for illustration only), and then in the field you'll be able to check and adjust your decision making to fit.