What was different about the NHL? It was the salary cup era.
What makes this AM contract unique is he is a star player a year away from free agency. While staying with the team, he took a massive AAV contract that was only four years. Other players in his situation, have either moved on to a different team or signed a long-term deal. I am not sure why you are arguing against this. I literally can't think of a single example of a star player doing what AM has done since the NHL has been like this (for at least 6 or so years).
Why you think the NHL 18 years ago is relevant is confusing. What was different? What i just described (what is going on in the NHL) wasn't going on. That is what's different. The norm wasn't you sign you star 23-25 year old to long term deals. Joe Thornton at 25 a year away from free agency? Signed a three year deal. It was a thing then. Now it is not, AM's contract is unique.
Again, I am not sure what you are arguing against. AM's contract is absolutely different than every other similar player in his situation the past 6 years at least. Maybe I am forgetting someone, but I don't think I am.