Assuming I'm reading the parent post correctly, neither of those links actually do what they would've been hoping for when moving browsers, even if they certainly get closer than nothing.

Firefox Sync only syncs with versions of Firefox, and Chrome's sync only syncs with versions of Chrome, so they'd have to switch mobile browsers too just because they switched desktop browser (and unlike on desktop, I've found Firefox for Android to generally be clunkier to use than Chrome for Android).

And that second link is about Chromecasting from Firefox for Android, not the desktop browser. Being able to send stuff from desktop Chrome is definitely a convenience someone could get accustomed to.