For real. I understand the security argument, but that poster and Mozilla in general seem to be making the argument that "no, you're wrong, you don't know what you want, we're going to tell you what you want, and it's a less feature-rich Firefox."
Well, I use Firefox, and I evangelize Firefox to everyone I know, on the basis, essentially of the extensions, and most of the popular Firefox extensions would have never come into existence with the new extension model. Mozilla is developing APIs to grandfather some of them in, but they're still reducing the possibility space from "anything" to "what we expose through these APIs", so new extensions that change everything will no longer come into being.
And aside from that, they don't even cover everything; I've already been notified by the developers of two extensions I use that they either can't or won't be switching over.
I really do have to agree with the people who are saying Mozilla has totally lost the plot. I've disabled automatic updates until I can figure out what I'm going to do.
This means I will now have a zoo of old outdated browsers. Safari 5.1 Win32, Firefox 56 Win32 with Firebug addon, IE11 on Win7 (plus Chrome, Vivaldi and Servo alpha)
I have hope in a lightweight reboot of Firefox based on Servo with HTML based UI (like Firefox was a lightweight reboot of Mozilla Suite; funny that Firefox is now many times more bloated than Mozilla Suite (now called SeaMonkey https://en.wikipedia.org/wiki/SeaMonkey ) and has less features)
(I use a separate Firefox instance for development, and it's not my number one browser for years because it can't handle hundreds of open tabs - IE and Chrome excel on that (my) requirement for 10 years.)
That's the entire point. Firebug could not have existed as a WebExtension, and thus without XUL addons the entire web development field could still be on Venkman or Script Editor rather than where it is now.
The XUL extensions model allows extensions in ways unmatched by WE, and yes the development experience isn't tremendous and it's a serious security risk, but that means it's possible to experiment or customise in ways WE don't allow. Users could get things like NoScript and greasemonkey and ad blockers and tree-style tabs without having to demonstrate its value to the browser developer and needing to get the tool itself or some necessary API integrated and merged into the browser.
> Most add-ons can be ported to webextensions. The ones that can't probably shouldn't have ever been add-ons to begin with.
That is utter garbage.