Because nato and the UN are the first sign internationally cooperation, but people want to shit on it because they don't have a good argument of why the structure doesn't work, so instead of creating a good argument about the current structure, they just shit on it and say "NATO BAD".
There is a reason why it is obvious to some people why NATO and the UN are bad and not to others. There are obvious good reasons to hate those organizations if you are the kind of person or nation who wants to do horrible things to other people or nations for your own benefit.
I'm not saying any of those people are wrong or right. What I'm saying is is people put forth the energy to criticize those organizations and countries involved without coming up with solutions to improve said organizations. Instead people just say that those orgs are evil or bad. Both organizations are international coops, so how is that a bad thing? It shows a great chance, but instead of trying to find solutions, they want to chastise it.
So with that being said, what would be your solution to improve NATO and the UN?
NATO, in particular, is highly coupled to the American/anti-Russian agenda. How much chance did Europe get to discuss the pros and cons of bankrolling a long-term conflict in Ukraine vs getting railroaded into it with the insinuations of being the next Chamberlain?
Even Xi Jinping and Vladimir Putin don't wake up every morning asking "how can I be evil today?" They may have a different agenda than the West, but it still comes from a place of caring for their country, legacy, and position. These are not wholesale foreign concepts. They can be understood and worked with. But I suspect the sort of organizations that would get the best out of them would require certain countries to acknowledge their place among equals and be willing to comptomise their sphere of influence.
Then do something about the problem! For fuck's sake. If you see a problem and choose not to do anything about the problem beside complain about the problem, then you're part of the problem.