Firefox is not really less hostile now. You can't even install and maintain local add-ons anymore. You can either install them temporary, and they are removed when the app closes. Or you must upload and sign them to their store.
I believe nightly edition and/or developer edition lets you install unsigned addons. Also there's a way to get an addon signed for private non-store use - can't speak to how that works, as my current project isn't quite to that stage yet.
