Now do you really think the reason they were traded was my point in bringing them up, or was it to say even the best are traded for whatever reason?
But the whole reason why either was traded makes those two examples irrelevant. If Ovi demands to be traded, you revisit. If the league somehow alters the CBA to allow you to sell players again and get money back in trades, you revisit. Gretzky wasn't traded, he was sold and players changed hands with the cash.
Absent those two completely unique and therefore not applicable scenarios, players like Ovechkin do not get traded. And please tell me how it makes sense for the Caps (who have a lot of work to do to keep their cap straight as it is) get better by dealing the best player in the trade, picking up ~5.5M in cap (4M with Connolly included)? If I'm the Caps, I keep Ovi and then I go and sign my Dadonov equivalent (player who can pot 20-30 goals with a good year) for around 4M.
Ovi + hypothetical 4M player who can do what Dadonov does > Hoffman, Huberdeau, and Dadonov.