It is diffiicult to understand because it's a falsehood. We're talking about PORN.
You can't cross over from "acting" to "acting." Professional wresting, playing your character, is actually pretty good acting training, like being on a soap opera. It's ACTING. Those aren't even real fights. They're scripted.
Actors don't "cross over" in the same way a porn star would. Actors try to move from tv to films but that is NOT the same as fucking on camera.
PORN: Fake name, explicit sex, big stigma. THAT would be a crossover, but it's never happened.
Who? Ginger Lynn? Only A-list things she did were NYPD Blue and Silk Stalkings. The rest were D-grade horror and nudie films and Skinemax but a lot of porn stars do those.
Sasha Grey? Thought she was going to be a mainstream star because Soderburgh put her in a mainstream movie, The Girlfriend Experience, but she got such bad reviews that was it.
If a porn star appears in something as a hooker or a stripper, not really a "cross over" just a willingness to do nudity.
A real "cross over" would be a regular role, no nudity involved, just acting. Could some do it? Some porn stars, men and women, can act. In the 70s that's how a lot of them started out, as mainstream actors. Jamie Gillis, Harry Reems. But no big studios or networks would hire them for that now. Too much bad publicity. Won't play in the South.
In Japan, no stigma. A porn star can quit porn, keep her porn name, get main stream jobs, and it's perfectly acceptable.
So, a porn "cross over" is not the same as a wrestler doing a movie.
Porn is acting. It's not all gonzo which, by the way, is also acting. And to claim wrestling is "good acting training" is a bit of a stretch. The Rock had one of The Best characters in wrestling but he's only a mid actor at best. Bautista, OTOH, never had a particularly compelling wrestling persona but he's an amazing actor.
I don't see why it matters if they play whores or prostitutes since they're still portraying another character. When Randy Savage portrayed a wrestler in
Spider-Man, he was still acting. He "crossed over." When Ray Allen portrayed Jesus Shuttlesworth in
He Got Game, he was acting. He "crossed over."
When Bella Donna appeared in
Inherent Vice, she showed no nudity. She played a "porn star," IIRC, but she could've easily been playing a secretary or librarian for all her character did. Traci Lords also showed no nudity in
Blade nor was she a sex worker even though it was rated R. They both "crossed over" even by
your standards.
I didn't know that about Jamie Gillis or Harrie Reems. I do know there was a Black actor, John Bailey, who appeared in
Good Times, M*A*S*H, Happy Days and
Kentucky Fried Movie who appeared in a porn called
New Wave Hookers with Jamie Gillis. He crossed over the other way.
So, yes, a porn star "cross over" is the same as a wrestler, musician, professional athlete or anyone famous in another field doing a film.
Edit: I just looked up Jamie Gillis. He did not start out in mainstream film. His first film is
Deep Throat Part II in 1974. He does only porn films until he stars in
Nighthawks with Stallone in 1981. From my quick research, Reems only ever did porn and never crossed over.