In Ryan v Zerban, Whose Idea Was a Debate Without Rebuttals?

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After watching the first Paul Ryan - Rob Zerban "debate," I wrote "nobody won the debate and nobody got schooled" and I thought, how could that be with anybody having a political debate with the ideologically-locked hyper-partisan Paul Ryan?

It didn't make sense until watching the second debate that I realized (and others did as well) that no rebuttals were allowed during the debate.

How do you have a competitive debate without any rebuttals?

It's worth noting that more than once during each debate, Ryan stated that opponents and others who don't agree with him shouldn't criticize, but should instead present solutions, does seem to imply that he is sensitive to being corrected or criticized.

So, whose idea was no rebuttals?