Comment by gaigalas
What killed Firefox was Electron. There, I just said it.
XUL was very good, but then it was no more. And as soon as it was gone, Electron apps appeared. It's a tragedy. Mozilla had everything to be in that place instead, with a better product.
Once that was gone, Firefox became just another browser, doing what any browser does. It's still very good, and my first choice, but damn I miss XUL.
I miss it too, but I don't see how Mozilla Prism can be related to the company's success or failure.
How do you suggest Electron makes money for OpenJS?
You can still make PWAs backed by Firefox:
https://github.com/linuxmint/webapp-manager
This has not made Linux Mint any richer.