This. But the migration was already apparent before Naruto ended. One Piece was pretty calm and had one of the most chilled posters back in 2008 and prior~ (referring to my time in Narutoforums website).
Fast forward 2-3 years later... the manga gained even more popularity and other fans from other competing mangas migrated over. You could tell that the topic discussions have become a steaming pile of excrement by these same shitty posters who came over from the Naruto and Bleach avenues (Narutoforums).
That's not to say that OP fandom was perfect and good back in the day. Some of them were pretty bad too, just not on the same level as the two other mangas I mentioned earlier. And yes, there are some great Naruto and Bleach fans who migrated over to One Piece as well.
Gear 5 didn't explode because the first episode reused animation and for lack of a better term, spent most of it jerking itself off + doing Super Saiyan effects (which felt insecure). Not to mention G5 had already been spoiled to hell and back by the time it arrived.
Delusional for sure though, some talk about it like its the Bible 2.
We should compare this when all 3 were airing.
Back in the days it was Naruto fandom that's the most toxic as 90% is powerscaling 10% about Sakura and some shipping
Right now as the other 2 are over, One piece gain more and more audience, new readers coming from different backgrounds, power scaling becomes toxic more than ever..........
This is also something to do with our current generation I'd day, more idiots on internet, so many underage kids touching twitter and other social media, ppl having issues with gender etc, all kinds of ppl join the fandom. Toxicity at its peak.