Except that's hardly what I see when people say they want a manga to fail.
They just want to be proven right because they can't accept that other people don't find the manga they like shitty.Even if it was what that they wanted to express, that still doesn't make sense to me.
Wishing for a successful manga to fail, which results in its fanbase being disappointed and the mangaka losing its job, for the hypothetical possibility that a manga they may like replace it just doesn't seem right for me.
are you going to whiteknight for Tite Kubo, of all people? does he really need you to defend him? The dude has made millions, is a household name among manga fans, and his series is (somehow) beloved by many people all over the world. He's at the top of his industry. I think it'll be okay if some people on the internet express how much they wish such a lame series would end, because it's just taking up space in the magazine.
it's like getting upset when people suggested Brett Favre should retire.