At the very least, Firefox's position on the similar <geolocation> element is positive.[0] I would assume their position for other permissions elements would be the same.
I seldom see visibility for any releases in popular browsers. The only time I notice any is if I don't use it for years, then get handed a work laptop that uses X browser. It's at least cool to see these docs even if I likely won't ever see/appreciate the element in use.
[0]: https://github.com/mozilla/standards-positions/issues/1288