The stupid part of this argument that no one considers is that Brady was the starting QB since wk 3 2001 until the end of 2019.
So, just like any team, you have the best player as the starting QB. That guy gets all the support, training, OC-time, practice time... and you fashion your scheme around him, and so on. So, saying BB isn't as good without Brady is like saying any coach would be the same with the backup QB playing. It's a stupid argument!
2008 shows that. Cassel was the backup and did reasonably well, but obviously not as well as Brady could.
2020 doesn't even count. It was a break-glass year. Cam was a stop gap, because for some reason BB was really caught off guard when Brady left. Cam is not a starting caliber QB. Neither was Stid. This is the first year since BB's first year with the Pats that he has another legit starting QB that isn't Brady.
Am I saying Brady isn't also better than almost all other starters? No. He's a generational player.
But, BB could have won about as much with the other "upper echelon" QB's of his generation (ie: Manning, Rivers, Brees, Ben, Rogers) and I'm betting he could have even won consistently with guys like (Pennington, Ryan, Hasselbeck, Palmer, Romo, Eli) Maybe not as much, or for as long, but the people who say it was "all Brady" don't know anything.