>>44761452I've played both (I've even nuzlocked Reborn's difficulty mod, Memeborn). I don't think Empyrean is even really in the conversation of hard fangames, it's just the endgame that has stupid stuff.
But yeah even then Reborn doesn't do the stuff listed, the bosses will have levels around the level cap outside of the boss monsters, and the leaders/bosses are mostly just monotypes, and it still manages to be decently challenging (though I think people's problems with it come from not fully understanding how to fuck with fields - a blind monotype sounds rough though. What type did you use?). Insurgence which was already said, Clover, the Kaizo games, the Dio_Vento hacks of newer games, the Reborn-likes like Desolation or Rejuvenation, etc etc. are all further examples.
There are definitely shitters like Dark Rising that go the way you described to make things hard but they're in my experience they're not the norm.