This is not the claim. The claim is that, empirically, many (or enough) of the women who end up in porn are underage, trafficked, or psychologically coerced (due to poverty, drug addiction, abuse, etc) such that the choice is not really the free choice of willing participant.

I am all for individual freedoms, but I've read enough about this issue, and seen enough documentaries, that I think the claim is very well-founded. Of course, some porn stars are just willing adults doing something they want to do, but there are many who are not.

Some argue it harms all women who participate in, but others argue it harms some women who participate, which seems undeniable.

It also ignores gay porn.