I talked about that actually.
Manning brought his offense to Denver and Tom Brady began bring in elements of NE's offense during the bye week in 2020. He went from running a scaled down version of Arians' offense to simplifying it and adding Patriots elements..lol. The next season, the Bucs offense looked closer to the Patriots than anything that Arians has ever drawn up.
Again, being a system QB doesn't mean that you can't QB. Mastering a system system for all those years is why they were elite. They know everything about it and while in that offense, has seen everything that can counteract certain things. That's how they got better with certain things. And this was actually during a time when skill actually mattered, instead of today where skill players outweigh QB skill.