I'm thinking way before she ran, even in NY, she basically avoided up state NY, winning on NYC and suburbs.
It's not even that you'll win those areas, the exposure to different people teaches you how to couch your messages to appeal to a wider audience, both Hillary and Romney were victims of "cell phone culture," the days when you could cynically rewrite your message to different audiences without them knowing are gone.
It's like the Kentucky governor who lost Trump counties, but by a smaller margin than Biden, and won the state.
The problem is by ignoring these states, you're not grooming the next James Carville, who understood the language of flyover country, and ending up with too many consultants groomed in Blue states who have no clue outside of their home turf.
The MAGAs and MSNBC crowd don't matter, we know how they're gonna vote, it's the 30-40% in between who'll swing this election. Biden needs people around him who can tailor messages to appeal to Republic women, independents and working class of all ethnic backgrounds (he's been losing black and latino working class men). The people who aren't comfortable with Trump or the PC crowd. Who want to feel they matter and don't want to be preached at.