Oh, really? I hope not in production builds, at least.
Defense in depth concept is not new either.
Defense in depth concept is not new either.
But yes, it seems to be something you can flip in production. The argument being that if you're in a position to flip prefs you already can break security in a million ways. It's not something you can accidentally flip either.
(The pref doesn't actually "let viruses take over the computer", it just turns off all the security checks)
Useful for some internal unit/integration tests for release and test builds, but really dangerous when pointed to the web.