It was really funny about a decade back watching the entire bike industry all at once acknowledge friction coefficients, and suddenly the tires all went from 24mm/90psi to 38mm/40psi. All because the roadies started riding on gravel.

You could argue that TPI tubes / tubeless made larger road tires practical. But we all secretly know it was because people at the time just thought thin tires looked cooler and "more aero".