If I had to hazard a guess:

- The HN crowd were likely burned the hardest by Mozilla's continued dumbing down of the browser (you'll reliably see complaints about how it seems like new releases always remove or move things needlessly)

- Firefox is de facto a Google project. If Google says jump, Mozilla says 'how high' because Google holds them at budgetpoint.

- Mozilla's stewardship of Firefox has been abysmal. A history of unforced errors, with a result of a completely irrelevant market share. (While paying a CEO millions to do... what, exactly?)

- Talking out of both sides of their mouth wrt. privacy (telemetry, cliqz and hiding it, etc)