Flawed teams can win cups and, in fairness, with increasing parity every year a flawed team will win the cup. But you shouldn't aim for those flaws and you can't ignore the strengths of the team that paper over those flaws. Are the Leafs likely to have Crosby and Malkin down the middle? No, so we can't be the Penguins and we shouldn't aim for it.
You can't just measure things by successes. Far more teams have been undone by a bad or mediocre defense in the playoffs than have won in spite of it. You have to play the percentages and they're pretty good that you need top quality defensemen to win.
This is super.
There are segments of the NHL (and fanbases) that see playoff results and let it blind their decision making, but the playoffs are essentially a Rock, Paper, Scissors marathon of luck and attrition, clouded by small sample sizes when evaluating individual performances. Teams that have the most talent and depth of said talent at every spot tend to win out most frequently in the regular season and the playoffs.
Some teams will tend to copy the champs by plucking their non-core players that have played themselves beyond cap constraints; teams ought to be looking to copy the formula that led them to acquiring those players when they were cheap/free (drafting), developing them into effective cogs in the machine, and then eking out additional value beyond their play when they get too expensive (trades) to replenish resources for step 1.