Monster Hunter fanboy here, been playing since the DS era.
These games are similar to Skate 1, 2 and 3, in the sense that your character technically does not level up.
YOU as a player get better at knowing your weapon, the layers of gameplay and the dance between you and the monster you are fighting.
It's incredibly rewarding to master a weapon in these games and top of that you have the build-crafting and load out system that really shines in the endgame.
You end up playing for fun, but also grinding materials to have f.e. "Hammer fire build" and "Hammer earplug build" and "Lance guard up build".
In the meantime monsters evolve, updates bring new variants and content AND you can fuck around with different weapons and have friends join you in the process.
Not to mention the fashion aspect. The incredible art direction and most importantly, the incredibly good feeling combat system. So darn rewarding.
I absolutely love this series. But it requires a certain "look" or "approach". It's like animal crossing or dark souls, if you try get into these games with wrong expectations you'll get frustrated and drop it. Enter with an open mind and you might just find the truest of true gems.
Edit: I didn't even mention speedruns on monsters, raid like monsters (Kulve Taroth) or the community and evolving meta of the games.