Yes, this will lead to situations where players will have stacks of a hundred dragons, and it won't be possible to build magic structures in castles above level 3, but we'll be making progress with Battle Doctrine!!!
And I think it will be possible to track.

The question is whether to allow it or not?

Because stronger and more experienced players are already creating such massive armies with weaker units that I wouldn't even dream of. And if they also get Battle Doctrine, it's game over.