Even with a "proper permission system" you can't ensure that there are no holes. For example, Badspot tried to design Blockland to be able to use mods freely without breaking, yet some add-ons still break the game, and there are even client-sided exploits that his permission system does not catch. He fails these add-ons, which is probably the best solution,
No, Blockland doesn't have a permission system. For an example of what I'm talking about, look at Android or Facebook (an application declares the permissions it needs (such as accessing the internet, or reading your phone book), you see and accept/deny this when installing the application.
Another thing, there's the difference between a blacklist-based approach and a whitelist-based approach. For example, Blockland is based on a blacklist, while RTB is based on a whitelist. While I'm fine with a blacklist as long as it's not abused, or a whitelist for a store/download center, the thing that's happening here is
embedding a whitelist into the OS. That is unacceptable.
because the other alternative is to destroy the freedoms of mod makers.
He's doing this all the time lol.
A "proper permission system" that catches all issues would probably be more restrictive than software control.
See the first answer.