I think it's a bit deeper than that.
People say they only bash Zoro b/c of his fans, but I think it's a chicken-or-the-egg situation.
Did Zoro's fans create the problem, or did people who already disliked Zoro find even more reasons to shitpost?
It's confusing either way. On one hand, he's a fictional character, so by all logical accounts it should be incredibly difficult to have genuine dislike for him. But on the other hand, it seems hard to believe that a single character's fanbase can have such a profound impact on other people's experiences.
For example, you can get me the most toxic and hateful Usopp or Franky fans, and I wouldn't give two shits about them.
I genuinely think it's because the character is Zoro that he and his fans are dragged into everything. It's because even within OP Zoro is like a human measuring stick. He gets compared with Luffy, Sanji, Kid & Law, he's had skirmishes against the Yonko, an Admiral, YCs, etc. Pretty much any important faction or character you can think of has been compared with Zoro at some point.