Nope, cause most of their arguments are so far out of reach that it could only exist in their head cannons and dreams. There is a fine line difference between what Oda WILL do to One Piece vs what readers WANT Oda to do in One Piece.
There was only ONE person I remember, back on Orojackson Forums,
@Celestial D. Dragon, who was able to convince me that Big Mom was truly gonna fall and meet her end on WCI, after the 2 of us had a long, intense and meaningful debate. That didn't happen, which I anticipated because the whole crew wasn't on WCI at the time.
But now Big Mom has survived all the way to the Wano Arc!
But i'm not all that happy for the win, because what's Oda doing with Big Mom in Wano is what he did with her in WCI, nothing but a plot tool. If i knew Big Mom was gonna be used like this in Wano, I now WISH that
@Celestial D. Dragon was right and Big Mom died back WCI so we don't have to put up with this crap in Wano! Big Mom having amnesia in Wano is worse than her screaming weddding cakkke in WCI!
That's about as far as convincing goes, every other theory hasn't convinced me is because of 3 reasons:
1. Something they WANT to happen, NOT something that possibly CAN happen, or make sense SHOULD happen. (Judge Top 5, Jinbe dying all made ZERO sense narratively and lore wise speaking). But people wanted it to happen for their own selfish reasons. Judge Top 5 was to give W's to Sanji so he can have an impressive background like Luffy's. And Jinbe dying in WCI was done so that he won't be able to join the crew and not threaten Sanji's position in the Monster Trio.
2. Most of the time its matchups and looking for W feats so people can masturbate to their favorite characters, those never end well. (Remember Sanji vs Katakuri 1v1 and Judge Top 5?)
3. Insufficient evidence or reasons to back up their argument or theory. Every time this happens, they would fall back on their last line defense which is
'anything can happen'. I remember
@Monkey D Theories back on Orojackson Forums used this argument a lot. Here on WorstGen Forums you see the 'anything can happen' argument a lot here too. It never helps.
Now speaking of good One Piece Theories and Theorists, Marco One Piece Theorist on YouTube is actually a good one with proof. He correctly predicted Kanjuro to be the traitor on Zou, something that Oda only reveals TWO arcs later.