SOMEone has to have control because left to ourselves, it is human to be selfish and demanding and we don't naturally give way if we think we're not done.
We here in FR are chock FULL of debate questions that we have formulated over (at least) a years' worth of conservative reading and debate amongst ourselves and WE have the natural tendency to decry anyone that doesn't think like us.
It just is what it is.
Perhaps debate questions should be submitted by the debaters ... they both look over the lists and argue between themselves which they will respond to and if they can agree, the moderator merely watches the clock
See #3. A moderator can be replaced easily by an alternating hot mic.