Mozilla has had the unusual situation of having an enormous revenue stream from Google. It is reasonable in that situation to build some adjacent things that support the mission.

Ah yes, this is why they fired the Servo team.

Mozilla has the unusual situation of having been fully taken over by a management layer that doesn't give a shit about the thing that caused that pile of money to flow their way. And the ongoing flow might even depend on Firefox remaining just underfunded enough to never compete against Chrome for real.

Nevermind the fact that Mozilla is sitting on a $1B fund that would be enough to do miracles in the browser space.