Why are enemies in levelling zones so easy?

idk if this is the case for new Shadowlands zones, but I’m finding enemies in Cataclysm old world zones way too easy to kill (compared to playing in Legion and early bfa). Often, I’m pulling multiple at once just to give myself a challenge but even that sometimes takes so little time it feels ridiculous.

And it’s not just Cata. During the demon hunter intro, the bosses that used to be a challenge solo even in bfa days are now dead in seconds.

Since I’ve only tried a few zones since the levelling revamp, I’m curious - are mobs more rounded in newer expansions designed for players with their full set of abilities or is this how it is in every zone? If it’s just a consequence of the new scaling, I hope they fix it. Levelling fast is great, and avoiding grind is part of that, but it shouldn’t be boringly quick to kill enemies, especially elites.