Air distance travelled is maybe 5% arm strength, it’s far more about the angle of release and how much air you put under it. Any NFL caliber QB, even the back ups and 3rd stringers, can throw it 50 yards. The question is does it look like a pass or a punt? Sure Josh Allen can probably throw it 70 yards versus Macs 60 but at that point you are talking at most 5 passes a year so who cares?
There is one route where arm strength matters and it isn’t the 50 yard bomb. It’s the 18 yard out. With proper timing it is indefensible, an automatic completion and first down. The problem is if the DB can break on it cuz it takes an extra .5 of a second to get there it’s a pick 6. High risk, high reward and Mac doesn’t have the arm to consistently make that throw. To your point a lot of the greatest QB ever didn’t and still won a lot of games. What Mac does have is impressive anticipation and touch so he needs routes where he can drop it in and let his receivers run, crossers, rub routes, and wheel should be his bread and butter. Even Brady, who grew to have an absolute gun for over the middle throws, had trouble with that out throw. Especially later in his career here, in fact his last pass as a patriot is exactly the route I’m talking and was exhibit one in my mind of why I was ok with the patriots moving on from him.