It was a "last hurrah" move. They had ridden G, Couts, Voracek, Provorov and Ghost through the last decade and were barely a playoff team - so either blow it up in the summer of 2019 or go for it, and with Holmgren still in charge, which strategy did you think they were going to pursue?
G gradually declined after 2019-20, Voracek has slipped substantially, Niskanen retired, Braun slipped to 3rd pair status.
Patrick and Frost never emerged, Myers turned out to be pyrite, the other young players simply couldn't pick up the slack.
Injuries and bad goalie play exposed that the window had closed.
Which is why firing Fletcher isn't nearly enough, until the FO, starting with Scott or his replacement, realistically assess this team, they'll just ask the next GM to make "win now" moves - even if better executed, they don't have the assets to successfully follow that strategy - and a Gorton or Rutherford type might strip their future 1st rd picks in a futile attempt to make that strategy work.