The first issue was how small the seats were—I was okay, but the smallfat next to me barely squeezed into hers, and Anna could never dream of fitting in one, even on her best day.
Anna could buy a seat in the disabled section, but it's usually not close to the stage, and any chairs that are available are not deathfat-sized (those generic metal folding chairs are typical).
Then there's navigating the stairs to get to and from your seat, which I imagine would be hell for a deathfat, especially if they're carrying an alcoholic beverage and a tray of nachos, which you know Anna would do. And it's a long, arduous, stair-involving trek to go get more booze and food, or pee.
I prefer standing in the pit, but she could never. She's got a decent height advantage, but she'd be in so much pain, and get so anxious about being touched on all sides and judged, and the heat of all those sweaty bodies around her would do her in. She could never.
Remember her trip to Coachella, where she got upset over all the walking and the heat, and likely some rude remarks, that she bailed early and went back to her hotel to lounge in bed? Yeah, that would be Anna's GA pit experience anywhere.
So I get why she likes small venues—depending on the venue, she can sit to watch the show. The bathrooms are nearby. There are few or no stairs. The bar is close at hand. And if she starts to get self-conscious and lose her mind, it's easy to get out of there (and parking's usually close by).