Why isn't anyone able to make a cut in movies?
Anyone?
Because anyone isn't suited for the field of acting.
It's no coincidence that the same big-name celebrities get the lead parts in major box office pictures. They're proven and reliable in bringing the numbers the studios need to make big profit margins.
Bodybuilders are meatheads who lift weights for money. What qualifies them for making it in Hollywood? Nothing.
Arnold is an obvious exception, and without his wife's help could never have made it in action films. You think he was the only muscular man with 20" arms who could wield a fake rifle and scream "get down!" in the 1980s? lol.
getting into acting is one of the hardest fields to break into. Literally tens of thousands try for a handful of parts every week. It's completely stupid and pointless if you haven't been doing talent shows and commercials since you were in diapers.