> 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."
