>The security benefit to consumers of blocking user scripts is probably a net positive for the average internet user.

Strong disagree. Extensions and User scripts are an unmapped wild west.

Providing a registry type system to securely vend packages/scripts is a very hard security problem.

https://www.bleepingcomputer.com/news/security/mozilla-block...

https://iamakulov.com/notes/npm-malicious-packages/