- Removing browser features (tab groups) by factoring them out into extensions, then
- Breaking the extension API such that such extensions are no longer possible, then
- Say you'll add new extension APIs to allow such features but actually don't implement anything for several years (https://wiki.mozilla.org/WebExtensions/TabHiding / https://bugzilla.mozilla.org/show_bug.cgi?id=1332447)
- Separately, break all extensions on the mobile version of firefox and then decree that the only extensions allowed on mobile must be specifically whitelisted by Mozilla