I tend to agree with the violence does not solve violence idea, but perhaps putting the player character into jail (a simple inescapable room should be ten lines of code?) would be a better punishment - and I suspect we shall see that soon as you rightly say online worlds become more perm and t
Some of them are just inescapable boxes; some of them look like jails; some are combinations of parkour and slow-blocks ("soulsand" and cobwebs, for example) so that the player can escape, it just takes skill and time to do so.
Because players can build them, but most other games need the "owner" to change the rules of the game. Gosh democracy, freedom, openness ... It's almost as if we just had an election:-)