One of the several reasons is OF throw to 3b about 10,000x as often as they throw to 1b.
Look at the stooges the NL trot out in lf just to get a bat in the lineup. Gordon hadn't even ever played OF til he'd been in the bigs a few seasons. Notice Moss (statue) didn't get put in rf. eff, I think we stuck Hos in left when we had billy. Remember Todd Hundley in lf?
Have you ever watched a game, ever?