This is a naive take. Of course these developers already permaban cheaters. Firstly many of these games are free to play so "getting another license" is a non issue. They're doing hardware bans nowadays which are harder to avoid but not impossible.

Half the battle is detection though. If you don't detect cheaters quick enough they ruin enough games that genuine players start getting frustrated and leave. Anti cheats help with this detection.

Probably every anti cheat idea you can think of, in terms of detection, prevention and punishment, has probably already been tried by a large online multiplayer game. It is an extremely difficult problem to solve, a constant arms race.