It should also be pointed out that Miyagi-Do was explicitly created by Daniel LaRusso to combat the impact Cobra Kai was having on the kids in Los Angeles.
Even pettier that he turned these kids against Cobra Kai which culminated into a massive fight at the high school that he should take some responsibility for.
In fact, Daniel ended up poaching some of Johnny’s students, so once again, it was just a petty move.
And really, it’s not like Cobra Kai was setting the world on fire.