I'm sorry, I should have clarified that my criticism was that these sorts of tools often get recommended as a security tool that can protect you from malware/spyware. There are still valid use cases for it like what TripMode for Mac is marketed towards.

Also if you're using it to prevent an app not to phone home, you still have to trust it not to do anything more nefarious than that, or simply spawn a program like curl (which you've probably allowed) to phone home for it.