Rebalancing Spellcasting 5e

[Trask]

I think the reason why such high level effects exist is because they are the sort of things BBEG Wizards and Litches should have and there is no reason to have different NPC and PC spellcasting systems.

But there already is an implicit difference, with all the rituals to summon orcus, hordes of undead minions, mind controlled slaves and whatnot that villains usually have in adventures. If a PC had access to every kind of magic that NPC's are implied to have by plot and such, it would be a huge problem.

I dont think it's bad that these things be separate because they exist for different purposes.