Much of this outcome I believe traces back to Mozilla's decision to drop support for embedding Gecko in non-XUL apps. Outside of Safari, WebKit's popularity is

Much of this outcome I believe traces back to Mozilla's decision to drop support for embedding Gecko in non-XUL apps. Outside of Safari, WebKit's popularity is largely owed to how easily it embeds — regardless of UI toolkit, platform, or language you're working with you can probably embed it, and so WebKit has shown up in countless embedded applications for over 15 years now. And while Blink isn't designed to embed as cleanly as WebKit does, Chromium can be pared down enough that it in itself can be used as a platform, which we've seen in Electron. While XULRunner was similar in spirit, it was cumbersome and clunky, which is why at one point one of the more popular Gecko browsers (Camino) was instead written with AppKit. Electron isn't exactly an elegant swan itself, but it's considerably more responsive and is arguably easier to write a passable application with. Embedding being killed also meant that there can only be one Gecko-based browser, because lack of embedding means being chained to XULRunner and prevents other Gecko browsers from being significantly different. So now if Firefox fails, Gecko is dead. If browsers like Camino still existed they could carry on the torch, but now those are gone. I know that embedding had serious technical issues but I think they were worth solving. By dropping embedding support they threw out the baby with the bathwater.