That's a long-winded way to say $0

> allows users of Firefox to download add-ons from their browser's UI and updates automatically, rather than having to manually pull an extension file from a Github page for each new release and install it.

only because mozilla is gatekeeping that away otherwise.

I agree with one exception:

> [...] and audience [...]

If you take into account small market share of Firefox and even smaller percentage of Firefox user needing uBOL then "audience" isn't anything important in this case. Perhaps this whole story will increase popularity of uBOL more...