The problem with scaling is two-fold - the first one is the inability to see your character's advancement, making it meaningless. The second is making the different creatures nonsensical. As in, it can make a lowly rat as powerful as a dragon because only the numerical stats matter, rather than the logical consistency of the setting. This was obvious in Witcher 3, where the mobs didn't scale to your level, but they did scale to the level of the zone, so a dirty hobo could be more powerful than a creature of legend you defeated 5 levels ago.
So which open world RPG did this right according to you?
Baldur's gate 2, where levels mean nothing until HLAs?
Morrowind had fixed important stuff and scaling randoms, that's one of the options in Deadfire. Witcher 3 is again one of the options in Deadfire.
The scaling in PoE1 didn't suddenly make spirits and ghosts dangerous when you're lvl 16, but made them not explode instantly. It's the same as if you remove the +ACC/DEF per level for everyone, who's only purpose is to make you able to outlevel content - the plebs still didn't get high level stuff, so you still feel your advancement.