Tbh though, there's advantages to doing it that way. Disadvantages as well, but the reason it never ends well in movies is a different thing than in reality.
A group of less experienced fighters can still wear down and "beat" an individual more reliably than rushing in all at once, particularly if they haven't worked together in that way much.
You do sparring in martial arts, and you'll eventually train against multiple partners. If they don't work together well, you can play them off of each other, even if they'd whip your ass 1v1. Even a concerted rush to take you down can fail if they aren't coordinated as well as coming as a group.
Thing is, it doesn't take much coordination for you to end up with your ass in a cheese grater.