However, the concept of levels forces the creation of a clear hierarchy of development (mainly of the castle), which limits gameplay variability. In addition, due to the very different strength of units (which is enforced by the level system), there is a problem with useless units – in the later stages of the game, even the first tier units are often useless.
I'm not saying that it's not necessary to have seven types of creatures per faction. Yes, seven types is a time-tested standard in Heroes, so why not? I'm not saying that you can't make these seven types radically different in strength. I'm just saying that you can do it one way or another, and standardization is evil. In the seventh game, they standardized so much that 80% of the champions are clones of each other and play the same way, just as tanks...