I think Fox does it right putting the show over the air.
Why wouldn't ESPN put Gameday on ABC, ESPN+, the ESPN app, and anywhere else.
No one subscribes to ESPN for Gameday. They subscribe for the games, and the whole point of Gameday is to advertise the games.
I know ABC has important airtime devoted to Wildlife Nation with Jeff Corwin and Jack Hanna's Passport, so maybe those shows pull in a huge viewership.