The parent is saying that it is in professional games, but that that doesn't mean it requires legislation making cheating in all games explicitly illegal. Penalties in sports are commonly enforced primarily through the organisations running the sport, and only some offenses even involve actual law. If you cause someone financial harm, it's very likely already illegal.

Match-fixing in professional games is clearly fraud, that doesn't mean that letting your friend win because it is his birthday should be prosecutable.

Cheating in physical sport is not fraud unless done with the intent to fix an outcome. Similarly, cheating is not always necessary to fix an outcome, but the penalty is the same.