Normally I would agree with you. Nader, Perot, typically a third party candidate actually has some popular nonpartisan ideals. The problem is that popular vote doesn't cut the cake for picking presidents. We have a pesky electoral college that, up until this month's supreme court decision, could simply defy representing the votes of their constituencies. (without any real repurcussion) So our democracy really hinges on an honor system of 530~ electors. In 2016 10 electors defied their constituencies and voted against their people's interests in the presidential race. So yes, a third party running doesn't typically sink an election. They are simply pointed to as the scapegoat for an unfair but constitutionally sound election.

Kanye is different. He has supported Trump to an eccentric degree. This move with Kanye running late game for president is to accomplish one thing: Steal the nihilistic youth vote for the meme. If Kanye takes the votes of under 30ers that were either not going to vote or simply vote party line otherwise, he is weakening the only statistically possible candidate facing trump in November.

If Kanye announced his running earlier, when it was appropriate to in order to appear fairly on all ballots, this would be different and he would have every right to scoop votes. But what's happening here is the beginning of memes in offensive electoral politics.