Nidai is right. In this poll from June last year, only 20% voted for Zoro killing Kaido:
I think what's happening on WorstGen is that the initial user base on the forum was heavier on Zoro fans than usual (due to how WorstGen started as an OJ splinter), and several of Zoro fans here (including myself), are very prolific and have written elaborate essays thousands of words and dozens of panels long to make the case for Zoro Killing Kaido.
To be honest, in terms of ratio of effort expended to shift in forum opinion, the ZKK gospel on WorstGen hasn't been very effective. Leaving aside the forum as a whole, most Zoro fans aren't yet convinced that ZKK will happen.
Speaking only for myself, I
really want Zoro to kill Kaido, but I can't say that it is what I think will happen. Regardless of how much I badly want Zoro to kill Kaido, I'm not yet genuinely convinced enough to bet on it.