[asiachick]

There's nothing stopping a 3rd party from making an Gecko version of Firefox. Electron is not run by Google nor the Chromium team. It's run by github (which only recently became Microsoft)

That said, I'm not sure what the point is. I believe (but could be wrong) that Chromium has more features that Gecko doesn't? So if you're choosing one over the other I'm only guessing most people would choose Electron

[sanxiyn]

"Electron for Gecko" was in fact done. See Positron discussion below.

[roca]

I don't have any direct insight into why the Atom people chose Chromium but I can see a few reasons that are more likely than "features":

-- Chromium was faster. (For Electron apps you don't really care about Web compat, where Firefox was ahead of Chromium for a while, but you do care about performance.)

-- Chromium was already multiprocess and had some other architectural advantages where Gecko was still catching up. So, less upcoming architectural churn.

-- Chromium had Google's resources committed to it. (Google's shine has worn off a bit since then but it's still a powerful effect.)