Like in what world are these issues comparable?

Everyone who already knows that Trump is a moron can’t actually develop a lower opinion of him.

Anyone who doesn’t know that Trump is a moron is too dense to parse anything more complex than a ten-second Fox News soundbite.

Thus, Biden giving a mediocre performance hurts Biden much more than Trump doing his normal word-salad oral diarrhea hurts Trump.

It’s not fair or logical, but it’s the way things work at the moment.