As others have said, it’s not just men that perceive that negatively; women do also. I can’t recall who said it, but feminism has meant that there are many different ways to be a woman now, but there is still only one socially acceptable way to be a man. The social consequences to men for being emotionally vulnerable can mean the loss of all social connections; I know that I lost about 3/4 of the people I thought were friends when I failed to successfully complete suicide. That creates a very strong disincentive to being vulnerable in the future.