I think there is some concern that scaling enemies would make going up levels FEEL kind of meaningless.
But how can leveling feel meaningless when it opens up access to more skills and talents, new and better looking equipment, sets you against new types of foes, can open up new quests, new storyline, and even new areas? In a game that doesn't use level scaling, becoming one level higher than the last monster you faced is still of little consequence if there are a plethora of same-level monsters waiting for you right around the next corner.
A lot of people would feel they're never really getting any stronger, since they're always on exactly par with the enemies.
Isn't this the case even if a game doesn't use level scaling? Even in Divinity : OS. You exit Cyseal's gate as a level 3 character and encounter carefully placed level 3 opponents. Eventually you run out of level 3 opponents, and if design has done its job properly you've accumulated enough experience to advance to level 4. Off to the next area we go.. where it just so happens level 4 opponents await us. Eventually we kill all of those encounters off and now we're level 5. What's over that next hill? Oh look.. level 5 opponents - even without level scaling.
This isn't the type of game with respawning MOBs where someone can decide they're just going to grind out the same low-level area for a while with their high-level hero. Unless you're the type to go mass-murderer in towns, the combat opportunities in this game are fairly finite, and there's just enough of it to make sure you can advance alongside it.
