I think about it the other way: there are lots of people that are uninformed and apathetic, they didn’t like trump, but think there isn’t a big overall difference between the two old guys. Those are the people that need to understand how bad Trump is, and how good (in a relative sense) Biden is as the alternative.
And, to some extent, to discourage voting. There are quite a few people who won’t ever vote Biden, but can be convinced Trump isn’t worth voting for.
I think about it the other way: there are lots of people that are uninformed and apathetic, they didn’t like trump, but think there isn’t a big overall difference between the two old guys. Those are the people that need to understand how bad Trump is, and how good (in a relative sense) Biden is as the alternative.