Because it still doesn't provide enough time to verify or refute any claims being made, especially when one sides strategy is to make a barrage of claims to trip up the other for as long as possible. If most people saw the use of that tactic as a clear sign of weak arguments and question dodging, it wouldn't be such a silly thing because it would server to expose that. But it turns out that kind of thing is a form of entertainment for many people and they like to watch their guy "win" against the other. That's a problem on both sides, but objectively a far more dangerous problem with the topics the right decides to utilize the tactic with.