The league's peak. In terms of rules. Where you could build and win with offense or defense. Players were allowed to hit and block hard without a hanky coming out was the early realignment years. 2002-2007. I was watching football well before that, so this is not nostalgia talking. I just remember how every year it was getting better and was amazed at how the league kept getting every thing right.
It was a cake and eat it too situation. You could have the Greatest show on turf. AND the Tampa Bay Buccaneers win with defense.
The start of the salary cap era right before it, would be a close 2nd.
Then in 2008ish multiple WRs got cracked hard coming over the middle of the field (as they should) in the same week. The lawsuit on going with the vets was on-going, and in came the defenseless player rules. That was the beginning of the end.
Naive me at the time thought it would be a phase, and once the lawsuit was cleared up in a few years time, it would start to creep back to what it was. The opposite happened of course. I want real football, the league wants the probowl for some reason.
The league has created rules, that all that essentially matters is QB, pass rush, CBs. You get those positions right you'll be fine. WRs are abundant in today's game so they don't matter as much.
Mainstream already knows this about RBs.
But more importantly it is a very soft game compared to back then. Put on a random game from say 1994-2007, and compare a game from 2021. It will look totally different and not nearly as physical, more like basketball on grass.