Tom Brady has arguably had the greatest career of any QB or any player ever.
However, if Tom Brady was drafted by my team, Washington, I am not confident at all that he even ends up in the GOAT discussion, let alone the clear GOAT for so many.
Football is just so situation dependent for QB's.
Putting it another way, I don't think Brady is equivalent to Jordan or LeBron in terms of talent. Brady needed a better situation around him to become what he did compared to those guys. But again, his career has been incredible and obviously he's been great.
That's very true, but it is also because football is the consummate team sport. In basketball there are only 5 guys on the court and they don't change after one team scores. Same with Hockey. Baseball is basically your batter vs. your pitcher. Football is the only sport where you really rely on a number of other people to be successful. It is the only sport where you can lead your team to a score, and then a whole other set of guys comes out to stop the other team. The QB is probably the most important guy on the team, but he can't control everything that happens on the field. He can't stop the other team's offense from going right down the field. Lebron James can drain a 3 and come back and block a shot. The QB can't throw a great TD pass and come back to intercept the other guy. You need a full team. And what you say is true. Johnny Unitas was recognized as the best QB to ever play the game for a long time. If he had stayed with the Steelers who drafted him and were a terrible team at the time, maybe nobody would even know his name right now.