As far as I know there is no known benefit, but for males at least there is the possible downside of very slightly increased risk of prostate cancer/dysfunction. Frankly it isn't that well studied, but it's worth saying that quacks, mystics, ascetics and charismatic leaders have claimed "nofap" is profoundly beneficial. It's also worth saying that they've never managed to demonstrate that alleged benefit in a satisfactory way.

The current movement bears all of the hallmarks of cults.