I had to scroll too far to find this answer.

Most of the criticism of it I’ve seen is about how the concept’s been warped to mean women aren’t putting out enough for specific men.

this is it in a nutshell. Men clearly experience loneliness, what’s problematic is the way “male loneliness” has been weaponized against women, as if it’s not a byproduct of patriarchy but actually a result of women’s neglect (or worse, an insidious assumption that women have an obligation to date men because they are lonely).