Moving the voting mechanism 'up' the hierarchy makes it more vague. People aren't going to bother reading individual comments to find the value, they'll just skim and get a gist of who won. These debates are built on conflict, and having a blow-by-blow (individual comment) voting system will always be more engaging and fun.
Cutting out the plebs makes it less rewarding to read the debate. Celebrity debaters will be required to overcome the lack of organic pull into the conversation. Why not just watch an interview between the two people?
What you are (correctly) describing is the status quo. But that is precisely what motivated me to try something different, even if it does end up utopian.
I'm not saying it will be a utopia, I'm saying it will kill the status quo. Which you will likely succeed at because the fire & flames that made the status quo popular is receding under the label of toxic and (soon to be) rude. You are in effect chasing the value of debates up into the smoke.
Cutting out the plebs makes it less rewarding to read the debate. Celebrity debaters will be required to overcome the lack of organic pull into the conversation. Why not just watch an interview between the two people?