Unfortunately we’ll have no way of ever really knowing will we? We can speculate all we like. But there’s no way to predict with any degree of accuracy how the musical universe would or wouldn’t have changed if one thing was just a little different.
So it’s an interesting speculation and argument. But that doesn’t make it a given. It might have been just as likely that with the state of bass amplification back then, the results would have been less than ideal and the bass guitar abandoned and ultimately seen as an experiment that failed. So maybe it’s just as likely the upright would have remained the bass instrument of choice had BEAD been how Fender tuned his first basses.
Aren’t alternate histories fun to spin?