They are, but indirectly. Witnesses work for the stakeholders. Stakeholders want to protect and grow the value of their stake which, at present, includes wanting to grow the user base (which includes communities and content providers).

If, hypothetically, stakeholders decide that users, communities and/or content providers are not a positive force in protecting and growing the value of their stake, and want to change priorities accordingly, there is nothing witnesses can do to stop that. Any witnesses who try will just be voted out.

Bottom line, this is a system based on stakeholder authority and interests ultimately. Everyone needs to decide whether they are on board with that. No one can force you.