It seems like you hear this mentioned all the time in referencing quarterbacks. Yet how often do you need a guy to throw it over 50 yards? A few times per season?
There's certainly an argument to be made that if a guy can throw the ball "over them mountains" then the defense has to cover more space. But as long as your quarterback has a decent arm and can put some zip on it when necessary; I would take accuracy, timing, and knowledge/understanding of the game every time. I've never thought of Tom Brady as having a rocket arm, but his place in NFL history is among the all-time greats if not the GOAT.
It just strikes me as a neat ability, but not a selling-point for why a given quarterback is great.