Why the limit on Heavy Tanks then? I mean, if what you say is true, I don't see a point in the heavy tank limit being 1. Yeah sure it's not the same type of unit but still, it's a limit, something which you're opposed to.
The heavy tank limit has two reasons.
First was that most of the heavies are tech free call ins. There was a period where avoiding tech costs and simply spamming late game heavies was the dominant strategy.
The second is that the heavies are (mostly) powerful generalist units. With a Tiger or King Tiger you can be reasonably confident in most fights. This is also why the Churchill is labelled a heavy tank but not limited - it simply doesn't have the offensive power that limited heavies like the IS-2 have. Following on from the first point, end game fights also turned into heavies vs heavies all the time. It wasn't interesting or particularly fun.
It wasn't an ideal way to deal with it, but it's what we got. Arguably there were also a few units caught up in it that had a "natural" limit anyway - few people every bothered with more than one Elephant or Jagdtiger anyway.