Well, Blizzard 2024 Diablo 4 developers have no excuse when there are over 2 decades of system ideas.
As it stands, we can have a full customizable follower, with skill tree and full equipment slots that can have emanate effects or being able to slot Ubers or Aspects.
Lots of ideas - I dont see why we are so limited. (and i’m not talking about just Merc. There is minion size, paragon properties, etc. PoE2’s minion tutorial trailer is so much more innovative and common sense.)