I think it's fine to dislike Oda's writing, whether it be worldbuilding, character-writing, whatever but I've never been a fan of people stating that something is objectively bad/good and that all the people who disagree are delusional or whatever. Seems a bit too pretentious to me and too much like trying to validate your argument with the belief that only your interpretation matters rather than just articulating your beliefs and letting opinions simply be opinions. People also seem to have different understandings of world-building, some seem to include the power systems while others don't so that also seems to cause further disagreement on these aspects of the story.
I don't really think people arguing about how significant the balance of powers is really means Oda didn't explain it well, people continue to bicker about plenty of things One Piece related for agenda-purposed or whatever. The Yonko are one of the powers that keep the Grand Line in check, the Navy does as well with the help of the 7 Warlords. Just because they're in balance doesn't mean they're all exactly equal in strength, just that the situation in the New World requires all powers present (or fitting replacements) to remain stable. One Emperor leaving to attack another, leaves them susceptible to an attack from a third party hence the system in place usually keeps the peace. Kaido and Big Mom wanted to ally to combat the Navy and to secure Ancient Weapons to really tip the scales for them (but Luffy's raid on Wano prevented that). The Seven Heavenly Warlords being disbanded and replaced by the SSG's Seraphim is also still a new occurrence and I feel like it's understandable to wait to see where this is all goes. Not sure this is all terribly explained. Even flaws in the system doesn't make the world-building objectively terrible.
Overall, I think Oda put a lot into explaining the One Piece world, the world government and the various factions in place. I'm not sure if the power-system would be included within world-building but if so then of course there are short-comings such as haki's explanation and how it compliments and counters the existing system of devil fruits and how it could've been utilised in a more satisfying way. But do flaws make it objectively bad? I don't think I agree and I think there's always room for discussion and other opinions.
