Because current manga all sucks and One Piece is all about getting stronk. You don't even know the story that you are reading.
Yeah is all about getting strong, that's why one of the most prominent characters is buggy, or why the power of luffy is literal laughter.
Not even once has luffy said his dream is to be the strongest. You know, the protagonist.
Luffy is all about freedom and shenanigans like that.
Naruto, Bleach, My hero, read stuff like that.
In one piece power is inconsistent at best, the focus of the story is adventure, the lore and freedom, and getting stronger is just a tool to convey the story, not the central narrative.
Just count how many panels are about anything except fighting.
Naruto is a good 70% fights only.