Why do they always do this in fighting tournament movies...? (Spoilers)

In fighting tournament movies, the badass villain that nobody can beat suddenly finds himself unable to any offense without cheating. This same thing also happened in The Big Brawl (1980), Bloodsport (1988), and Kickboxer (1989).

The film built Horn up as a mauler and he had no offense aside from that cheap shot at the beginning and what he was able to get after the bad guys rigged the gravity control so that Steve couldn't dodge. 0% of his offense had anything to do with talent.

That's my one real gripe about this film. I don't expect it to be Shakespeare, but I hate when a movie builds someone up as a tough guy and then makes them out to be entirely dependent on cheating in the end. If the champ's a fraud, they should let us know well in advance. If they're legit, they should be legit when the hero challenges them as well.