I don't know that there can be a blanket answer for this. The make-up of founding teams is wide and varied.
As with any meeting, I suppose it comes down to the degree of value for either group that would rely on the presence of any party.
Smart companies operate efficiently. It doesn't always have to be a dog-and-pony show. If the attending parties can speak well to points of discussion and equally capture items to effectively communicate to the rest of the team concisely but meaningfully, then that should suffice.