The question started by a joke about t*he hell for tall guys to find fitting T-shirts, like size L shows your navel every time you raise the hands, and size XL expect you to have some beer belly so you end-up floating on the clothes. Somehow at that poing better get a navel piercing and wear a crop tops like ladies do. *
So why did crop-top never became popular for men ? There was a few designer trying to sell some. But it’s not something you’ll see in the wild.
I can hear the whole But we’ll see overweight middle-aged men hairy bellies but it’s not like middle-aged overweight women don’t exist.
Because being tight is considered a beauty standard for women, not so much for men. For men this is mostly upper body muscle (shoulder, arms). A vest top would he an equivalent, and you don’t see skinny guys wearing that either.