I agree that if Biden loses, the analysis will show that Trump had a stronger ground game in certain states.
However, I also think that you can argue that Trump is making a similar tactical error. For example, Trump has campaigned quite a bit in Florida, North Carolina, and Ohio -- and while he does need those states to win, I think you could argue he should be spending his resources on states that he needs to flip. Basically, at this point in the campaign, Trump needs to just cross his fingers that he'll win FL/NC/OH, and then focus entirely on closing the deficits in Pennsylvania, Michigan, Wisconsin and/or Arizona.