Users are still allowed to install any extension from outside the garden they want.
It's yet another hoop to jump through, one that further splits "developers" and "users" and makes it harder to be a "casual developer" - one who just wants to make an extension and share it among a small group.
> one who just wants to make an extension and share it among a small group.
That's a fair point, but I don't think it's that bad. I do this all the time with Chrome, which already has walled garden:
"Hey guys, I made a Chrome Extension that inlines all the images in our shitty issue tracking app rather than having to download them all. Extract the zip, visit chrome://extensions, enable developer mode, and load that folder."
Except in this new scenario it's install a different version of Firefox (Firefox Developer). Good luck with that on many work machines. My dad is unable to install any applications on his work machine but he was able to install Adblock for Chrome the other day. So had he wanted to install this hypothetical extension for Firefox he would have been unable to.
