I have no problem with the NFL "encouraging" teams on guaranteed contracts. But there is a difference between encouragement and actual collusion. Given some of the contracts that have been handed out since the Watson deal, my guess is teams did not head the NFL's encouragement. Just because there have no been anymore full guaranteed gargantuan contracts does not mean there was collusion. The Brown's deal with Watson was the height of dumbness. I am sure every other team in the league was smacking their head in bewilderment.
Now, if you want real collusion, out in the open and 100% provable, look no further than the league punishing Dallas and Washington for exceeding the salary CAP the year when the CBA had expired and technically there was no salary CAP. The NFL held the owners to the old CBA despite no legal justification, then penalized Dallas and Washington for violating a non-existent rule. Clearly, the league told teams not to exceed certain limits on contracts and the teams agreed - except for Dallas and Washington. Even more incriminating is the fact that the NFLPA did not file a grievance and the two teams did not file a lawsuit. Obviously, there was some kind of back room deal sealed with a wink or a nod. Dallas and Washington appealed to the league and lost, but never took the matter to court, probably because they feared retribution.