I have to wonder why that's a bad mechanic in principle, too. You'd think you'd want the game to actually make you work to play it, instead of having to slaughter a thousand Level 1 Slimes or whatever if you happen to wander back to where you started.
I consider it to be an inherently bad mechanic, in part, because it has never been done correctly, and I have no hopes of it ever being so.
E.g., In FFVIII (ugh), Leveling up actually made the game
much harder. It was not out of the question to, after power-leveling near the end of them game, run into an early mob that had well over one million hitpoints! At a maximum damage of 9999 per hit, guess how long it takes to beat one of those.
E.g., In TES IV (vanilla), equipment and quest rewards scaled with your level, meaning that it was more beneficial to grind your way up to the maximum level (ugh) before doing
any quests. That's not even taking into consideration the fact that your level had no purpose, because you could kill ANYTHING at ANY LEVEL,
especially if you were prepared for the fight.
E.g., In Fallout 3, I would routinely encounter Super Mutants (including giants) before I reached level 4, and wiped the map with them, but the same exact enemy would give me more trouble 3 levels later, regardless of where the encounter took place. THIS MAKES NO SENSE.
I have never seen level scaling handled in such a way that it did not destroy either my willing suspension of disbelief or my enjoyment of the game mechanics, and I consider it to be an inherently bad game mechanic.