> It's baffling actually that Firefox doesn't let you annotate bookmarks, it seems such an obvious feature.

There was a financial conflict of interest, since Mozilla Corp was selling Pocket subscriptions where the ability to even just be able to have an unlimited number of highlights was a premium feature.

Firefox has an experimental Tab Notes feature now: <https://support.mozilla.org/en-US/kb/tab-notes-firefox>

(In the Firefox heyday, the bookmarks manager had a Description field that could be repurposed for adding notes.)