To Biden’s campaign, attendance figures are a meaningless metric. Focusing on crowd size is Trump’s game, they say, an emphasis on style over substance that attempts to turn audience engagement into an argument about the 76-year-old Biden’s energy level.
Crowd size, after all, is an imperfect metric to measure a campaign’s vitality. While it can be a revealing indicator, it still lacks the scientific underpinning of polling or the fixed-dollar figures associated with fundraising. Nor does it account for the judgment of elected and influential Democrats across the country.
Lying (or being delusional) about crowd sizes was Trump's game, not focusing on them. There's a bit of delusion going on here, too. And of course "crowd size... is an imperfect metric" but they all are.
As I said, if you only get 6,000 people to show up in Philly, somebody is doing something wrong. That might not even say much about the candidate, but instead a failure of the people he has hired to get people to show up. But that's an issue too, especially if they're the type of people who run to the press and say "oh no our failures are actually good."