"Largest" is a weird word for Vulture to use. "Anne Hathaway is a large movie star!"
Anyway, I'm not sure I'd necessarily call her that much larger than Matthew McConaughey, Woody Harrelson, Collin Farrell, Toni Collette, Kevin Spacey, Laura Linney, Jane Fonda, Lily Tomlin, Jeff Daniels, Michael Sheen ... But they did say "arguably."
In any case, congratulations to Anne! However large she is compared to the others, she's great, and TV is where it's happening these days.