It's just someone creating a pull request to the dmca repository with the pull request containing the entirety of the youtube-dl repository (and its history). It's mostly a joke
I've had the exact same experience you described. Realizing i3 is the way to go and apps shouldn't manage tabs themselves - trying to stop Firefox / Chrome from doing so - realizing it's not simple and the no tabs extension is problematic. Trying qutebrowser and giving up because it's limited.
I've settled on NoTabs Firefox with a userChrome.css that hides the tab bar until Firefox someday supports native no tabs.