Comment by Wowfunhappy

Ah, but note I said "mainstream browser engine", not "mainstream browser!" The mainstream browsers themselves dropped Mavericks some time ago, but other developers have been maintaining backports.

Firefox Dynasty is actually a relatively recent development. For a while I was using Chromium Legacy[1], which, yes, did stop getting updated a little over a year ago. But then just in time, i3roly came along with Firefox Dynasty[2]!

It's true that if i3roly drops Firefox Dynasty, and the Chromium Legacy developer doesn't return (there has been some movement on the repo), that will be the end of this project. But that could be many years from now!

1: https://github.com/blueboxd/chromium-legacy 2: https://github.com/i3roly/firefox-dynasty