Yes all those teams had strengths.
It doesn't change the fact that LA has consistently been one of the lowest scoring teams in hockey, even with their acquisitions. They are consistently near the bottom in goals for.
It doesn't change the fact that Pittsburgh had a defence with Kris Letang as the only real piece that fit his role (seriously the rest of the D was Trevor Daley, Olli Maatta, Brian Dumolin, Ben Lovejoy, Justin Schultz). Thats a bad defence.
It doesn't change the fact that Chicago's #2 centre in their cup years put up the following stat lines.
2010 Dave Bolland, 16 points in 39 games regular season
2013 Michal Handzus 0 goals 12 points in 27 regular season games.
2015 Brad Richards 37 points in 76 regular season games.
2nd Line Centre was a major hole on those three Blackhawks teams. Thats a fact.
All of those teams had strengths, and they also got a bit of luck... Bickell going on an unsustainable playoff scoring tear. Bolland putting up 8 goals and 16 points in 22 playoff games the first year. Tim Thomas playing otherworldly. Jonathan Quick getting super hot. A rookie goalie coming in and shining for the Penguins.
Thats what any team needs to win the cup. A good core. Some strengths, and some guys getting hot at just the right time and helping you win. 30 teams, 16 playoff teams, 1 winner. It takes skill and a little bit of luck in this cap era.