Parity doesn't mean that great teams one year automatically become bad teams. It also doesn't mean that there is random number generator where every team every year has the same chance to win. Parity means that over the long term every franchise has an opportunity to succeed - not that every organization will succeed. See the Buffalo Sabres. (Sorry Buffalo fans - just the most recent example of this phenomenon). Historically (which I consider to be post expansion but pre-salary cap just based on my fandom) - "large markets" had huge advantages where they could have TRIPLE the salary of small market teams (EDM vs. DAL back in the day, or the Cup finals with COL vs. FLA or WASH vs. DET). That was the definition of lack of parity.
IMO, teams are the amalgamation of front office decisions. Teams that tend to make good decisions (which I would consider FLA & DAL to be two of those cases) have sustained success. Even a team like the Oilers that got lucky with winning the McDavid lottery made great drafting decisions with Draisatl & Bouchard, and some very good other decisions like Hyman. As a Hawks fan, teams typically go south when their "good decisions" age out (typically when overpaying their own UFA's) and the talent pipeline dries up.
This year is the combination of a team with amazing team construction (FLA with good core drafting of Barkov, Lundell, Ekblad, etc., successful reclamations of Forsling, Bennett, Reinhart, Mikkola and good deadline acquistion of Jones & Marchand) vs. a team with 2 of the top 4 players in the game who is also getting great depth contributions as well.