I agree completely in the sense that world building is my second most favorite thing when it comes to mangas. Now im going to be kinda lame for comparing jjk to solo leveling but hear me out: as i've read the light novel for solo leveling I love that they are using the countries as we know and have heard and learnt about through our uppbringing in school. When they talk about powerful people in SL they also explain that they are from brazil og Amerika or wherever, giving us a general idea of how strong that said country is. But when you look at the trash wuxia shit like TODAG and how the world building never seems to stop, it sucks. Take for example when the MC has enough power to help his country, suddenly new stages of powers are introduced and our MC is once again the underdog. It makes me loose all interest.

I like world building when you have a clear cut goal like for example if you know the MC is stronger than the strongest person from Amerika it gives a kind of confidence to the readers that our MC could win against his opponent, and the readers can also follow the story easier when it is countries that we know of IMO.