People seek confirmation that their negative traits are positive ones. Why put in effort to win, when you can just get an echo chamber to explain to you that you already won because of XYZ reason.
This isn't limited to the manosphere stuff but it certainly is a big part of it. Any group that uses that other people are full of shit though as evidence that they are the good guys is also trying to pull the same trick.
There is value in feminisim because women's rights are "new" and that is to say that there are people alive who grew up in a time where women's rights were considered a joke. Women received the ability to have their own bank account without a man co signing in 1974. That means MOST Gen X people, when they were born, their mothers were not legally allowed to have a bank account. That isn't ancient history like some folks like to act it is.
Sharing your opinions of how others chose to dress or act is weird unless you are doing it to influence others. Trying to influence people by belittling them is rude.
You could be saying it about how someone dresses, or dances, or what bike they chose to ride.
It is unfortunate that men belittling women about their makeup is so pervasive in our culture that after at least three generations of people highlighting how hurtful it is, people still think their right to state their opinion of random people is more important than people's right to go through their day without being accosted.