The comment you replied to didn't say that masculinity is an antiquated idea. It said that an ideal of masculinity is antiquated; that is, one particular ideal

The comment you replied to didn't say that masculinity is an antiquated idea. It said that an ideal of masculinity is antiquated; that is, one particular ideal of masculinity, not the idea in its entirety. You may disagree with that too, which is fine, but it's a different thing than you responded to. Different people see themselves in different ideals of masculinity.