Practically all NBA and MLB contracts are guaranteed. It's not that big of a deal, financially. Especially considering the value of these franchises (Washington is about to sell for over $6 billion).
The NFL has been able to not guarantee contracts forever because...no one offered them. Then one team offered one QB a fully guaranteed 5 year deal. Not the richest franchise. But a franchise that wasn't going to get what they considered a franchise QB any other way.
We had what, a dozen teams entering this offseason needing a franchise QB. And an age 26 former MVP QB with a 73% winning percentage who is arguably as good, if not better than Watson. And no one signs the guy to an offer sheet that only cost 2 1st round picks? Trey Lance, a small college QB with one year of experience, cost the Niners 3 1st round picks. Watson, with all of his misgivings, gets 3 1st rounders + in return. Jackson? A huge bargain for 2 1sts. No bites. None.
But hey, NFL teams are just being smart. Like signing mid level QBs like Carr and Jones for $150 million. They're so smart. No collusion at all here. Nothing to look at.