Continuity mistake: Miguel kicks and breaks a staircase railing during the school brawl. For a second it cuts to Robby. When it cuts back to Miguel, the railing is fixed.
Revealing mistake: When Sam and Tory confront each other at school, the same extra (a girl wearing glasses) appears in two different places. She is behind Sam during the confrontation but Robby also runs past her in another shot.
Continuity mistake: During the school brawl, Miguel tries to stop Tory from further hurting Sam but Tory kicks him aside. Tory's jacket comes off her left shoulder. It then cuts to Miguel and when it cuts back to Tory, her jacket has come off both shoulders.
Continuity mistake: Miguel and Hawk are in the same class when Tory hijacks the announcement. When she meets Sam in the hallway, Hawk is now in the crowd behind Sam, but Miguel is just leaving the classroom and running through the halls.
Continuity mistake: During the school brawl, a teacher tries to break it up only to get body slammed. Hawk is flinching at this in the close-up. In the wide shot, he is kicking someone.
Answer: Just like in the original film, some guys want that brutality. Johnny in part opens the dojo because of his past rivalry with Daniel and to train a kid that's being bullied. But also, other kids that are being bullied want to join in order to learn to fight back. Johnny is also teaching the Cobra Kai creed (Strike First. Strike hard. No Mercy.") so that's why he opens his dojo with that name and the old Cobra Kai dojo's past reputation is exactly what he wants to elicit.
Bishop73