The thing with scalable enemies is that their levels scale but their equipment doesn't. So like in Skyrim, enemies scale, but they become so easy after a certain level because you have great equipment and an arsenal of abilities.
So you feel a sense of accomplishment without enemies being ants.
That is, until the game scales equipment too and then you start getting weak messengers hand-delivering new weapons and armor to you with no cost and little effort. Skyrim is guilty of this especially.
Humans have a natural drive towards exploration
And that sense of discovery is harshly stunted when the player realizes he can go anywhere he pleases in an often generic and repetitive world, and find the same challenge everywhere. Making so that the player can literally pick any random direction and find no consequence if they simply go out that direction and not stop. If the sense of exploration is key, one would either repair the faulty battle scaling, or undo it altogether and put more effort into creating unique and appreciable environments.
Not when the enemies have a "lowest possible stat" - a Super Mutant should remain a Super Mutant - a fight with a huge monster should be challenging regardless of when you meet it, but it can't be downgraded to an idiot-like level - it needs to be balanced.
But, they thing is, they often are scaled lower. Even if there's a hard-limit to the lower-scale, the enemies are still usually manageable with a little effort, and once the player learns how to tackle the enemy, they become just as predictable and generic as the other enemies that do scale beneath the player bracket. And even that, actually, makes very little theoretical sense: to have a low-bracket
beneath the player level or even at it means there will always be a scaleable setting that's push-over for the player, something's that's always accomplishable and something never too dangerous to engage with. If there's lowest-scale that the player can reach, that means that inevitably, the game will cease to pose a threat (which is often at a very low level in games that scale content).
Difficulty is a hard thing to properly balance, especially in a game whose main goal is not to have good difficulty, but to make enough money to compensate developers' and publishers' financial investment. Next to that, it's hard to properly accommodate every player's idea of an ideal difficulty. This is, thankfully, mitigated on PC versions of games, where users can at least have the chance to modify such scales and put in something more constant, dependable, and dangerous to deal with. In the end, at least, no broken difficulty scale I've encountered has destroyed a game experience. It's only made it a good chunk less appreciable.