You don't think DeVonte Adams, Jordy Nelson and Randall Cobb in their prime were comparable? And GB didn't have Zeke taking a share of the offensive load.
Clearly Rodgers could have put up more than one 300+ypg season, but the Packers were worried about winning, not just piling up all the passing yards they could.
The point is, it doesn't take passing for 300+ yards per game to get to have team success, much less the 325 you mentioned for Dak. In 2019 the Chiefs won it all with Mahomes throwing for 288 ypg. The Pats won in 2018 with Brady throwing for 272 ypg, AND with the 5th best rushing team in the NFL. The Eagles won in 2017 and only averaged 248 ypg passing, but had the 3rd best rushing team in the NFL. In short, teams don't feel they have to put up the best fantasy passing numbers to win. It's all about how to move the ball and control the game.
And no, they didn't pay Amari that kind of money not to pass it, nor did they pay Zeke that kind of money not to run it. They paid that kind of money to have all the weapons they could - so teams couldn't load up stopping one aspect of the team without getting beat by another. Besides, they can still pass it plenty without Dak averaging 300 ypg, much less the 325 you talked about.
As for passing more and more every year, Jameis Winston was the only QB other than Dak that threw for over 300 ypg last year, and there wasn't a single team that was interested in him as a starting QB for 2020. Teams don't want to throw just to throw, they want to control the game, and it that can be done without throwing for 300+ ypg.