The issue you linked is specific to the `about:` pseudo-protocol. uBO's WebExtensions version works as intended on the web.
WebExtensions currently fall short when it comes to any addon that modifies the UI significantly (tree-style tabs etc), though it's been mentioned in some other comments here that they're talking to addon devs to extend the API where possible.
The irony is that since most people have DNT disabled having it enabled would make it easier for you to be tracked.
> it appears that Mozilla doesn't intend to let addons run on `about:`.
Why is that?