Oh I totally understand why Mozilla did what they did. It was the logical step to make Chrome addons available on Firefox, abandon the structure XUL imposed, and migrate to Servo-based components. But while they promised a better WebExtension standard (which I defended at the time), they didn't deliver. They needed more time to improve the API and make sure the most used extensions were ready[1]. Developers needed more time too to totally change the architecture of their addons.

And today, they're not ready. And they won't be in six weeks either.

[1] https://arewewebextensionsyet.com/

Edit: [1] answers "Are we WebExtensions yet?" as Yes. I don't agree.

Well they gotta make the cut at some point. If Firefox waits forever then Chrome will just eat up all their users.

Don't listen to the stragglers who want all the old Firefox behaviors supported forever. The wast majority of users don't care about Tree style tabs and vim style keyboard navigation or what XUL even is. They just want something snappy and fast like Chrome. That's how you get users to use your browser. That's how Firefox became popular in the first place. That's how any browser ever became popular. Yes even IE was faster than Netscape at one point, maybe because of nefarious practices by MS, but it was faster, and that's what the users wanted. It's all about the speed.

It's because of the killer combo of increased sandboxing, multi-process architecture and performance constraints.

I think they couldn't keep everything together with the degree of access old plugins had to Firefox internals. So at some point they had to rip off the band aid.

Multiprocess already shipped. One of the reasons extension developers are frustrated is that Mozilla told them to make their XUL extensions multiprocess-compatible and then told them they'd have to throw that work away.

Notice how I carefully avoided your strawman. There were several reasons for their action. I listed what I believe are the 3 main reasons.

They did have the choice to not ship the increased sandboxing, multi-process architecture and performance constraints until three months after the new extension APIs were ready. They didn't because they thought the trade-off wasn't worth it.

They really couldn't. People don't do things until pressured. Look what happened with Python 3. It took 10 years for it to reach Python 2 parity in terms of packages...

The problem with WebExtensions has been Mozilla not providing APIs, not extension developers dragging their feet.

I really do miss the slow and methodical Mozilla that was not out to chase the latest Chrome fad...