That isn't what I said though. Obviously men who start a family but don't do the childcare won't be negatively impacted. I'm not talking about them. I'm talking about the ones who do curtail their careers to do the childcare. This is a less common arrangement to be sure, but I know more than one heterosexual couple who has done this (usually because the woman has a better paying career).
That's my entire point. They're not equally impacted because there are larger societal pressures designed to punish women who want to continue their career and men who want to spend time with their children.
Read what I said more carefully. I didn't say all men are equally negatively impacted. I said the men who choose to take on the burden of childcare are equally negatively impacted.
And I think you need to reread my argument, which is specifically talking about those men who do take on the burden of childcare against the societal pressure to do otherwise. I think it would do you well to reread my argument from the top because it's starting to seem like you're arguing against something entirely different than what I'm saying.
I don't think this claim holds up to scrutiny. Yes, there are men out there whose careers are negatively impacted by starting a family, but by and large the expectation is a man continues working while a woman drops everything. That's part of the reason why family leave for men is less common.
Which boils down to structural sexism being an issue for both men and women. Men are not allowed to spend time with their family and women are expected to drop everything to take care of the children. In a more equally balanced situation, men would have the opportunity to be the full caregivers while women could continue their career in their field of choice. But right now a lot of options for families depend on your gender.