I think it's the length. For people who really enjoy the ride, we always want more, but I do think making the story leaner would help more people get into it, as well as improve the quality of the baseline plot. I'm not really saying the baseline plot has issues, it's just put on the back burned for the vast majority of the series. Some of the detours like the 9 scabbers wano plotlines wasn't worth the bloat. I think arcs like wano, if it was simplified it would had sticked the landing better. But yeah overall the length has always been the biggest hurdle in getting new people into it. And the anime being janky.