In my opinion , the positions of chair, treasurer or secretary do not confer any extra powers to members. The act is very specific in that these positions have certain functions, but no extra power.
Of course members who attain these positions often assume xtra powers and become roadblocks to a democratic process. They justify them maintaining these positions because ” no one else can do it” or some other excuse
In order to break this entitlement, you need to get them removed from the committee completely.