You’re right, but in order for someone to fill his role or even a portion of his role, they need to be able (and WILLING) to do those things.
There have only been a handful of ex QB’s who’ve transitioned to other positions in the NFL and actually been successful, and none have succeeded at multiple positions/roles like Taysom has as a QB, runner, blocker, receiver, and special teams player.
Finding a running QB that can come in on some downs and get some yards is easy to find, the NCAA is full of them. Finding someone that can actually do all the things he does consistently is not so easy.