Rumor: "Pale Moon is just a rebranded rebuild of an old Firefox version"
FALSE
Pale Moon has been on a divergent path with its own code for a long time already. It was a rebuild in 2009, yes. It was a rebuild with minor changes in the Firefox 4.0 era, yes. But we've come a very long way since then with an increasing amount of different code being carried over each time it was re-based on later Firefox code. It's a true fork now and has been employing rapid development (as opposed to rapid release) to solidify this independent direction with its own focus and attempt at keeping the browser sane, lean, and offering users choice and stability.
At the same time, Pale Moon's focus on security and evolving networking standards has added features and kept pace with those developments in other browsers, by e.g. adding TLS 1.1/1.2 support a while back, by offering OCSP-stapling, by keeping a close eye on encryption and the browser's security by continuing to port or re-implement security fixes that apply to Pale Moon as a browser. It is neither old nor outdated, it is not a "rebuild" and it does not use obsolete technologies or have security holes.
They're released on a much slower schedule (once a year) and get security fixes backported. They're intended for big organizations that don't want 6-weekly updates and are willing to live with outdated software.
But obviously its also handy if you want to fork and can't deal with re-basing every 6 weeks. Especially if you don't intend to update your fork a lot. You still get the free security fixes.
Stripping out features that are lazily-loaded JS files and in return being stuck with outdated stuff feels like a very weird tradeoff to me.