I didn't say QBs couldn't "pass" in that era - I said it was tougher and you weren't getting a large amount of QBs with high completion percentages, a lot of 4,000 yard passers, or even 30+ TD passes a season.
I also stated, despite defenses being tougher, Brady still ranked high during that era - even leading in passing TDs in his second year starting.
In 2018, there were 2 5,000 yard passers, 10 4,000 yard passers, the average completion rating was around 66%, 3 players had 9.0+ YPA and 6 with 8.0+ YPA, and 8 QBs with a QBR above 100
In 2002, there were 4 4,000 yard passers, the average completion rating was around 62%, no QB had a YPA above at or above 8.0, and only 1 QB had a rating above 100.
Did QBs just get better or did the NFL rules when it comes to penalties and recent CBA agreements hurt defenses more than the offense? I can pull the quote up for you about Tom Brady talking about this if you'd like.
As for Dak "outperforming" - In Wentz second year, he was runner up for MVP and helped put his team in position for a Super Bowl victory. Goff also took a major step and got the Rams to the playoffs for the first time in what, a decade? In most statistical categories, Goff and Wentz outperformed Dak in 2017 and 2018. You inflate Dak's stats by including his rookie year - that was over 2 years ago. A lot changed.