Yeah, I agree with you there. Scoring is the issue in the playoffs and has been for years. It's an entirely different (and darker) discussion regarding whether there truly is league parity, but here are the past three years' cup teams and their forwards drafted in the top 15:
2024: FL (Tkachuk #6, Barkov #2, Reinhard #15); EDM (I mean... this speaks for itself)
2023: FL (same as above except for Reinhard); LV (Eichel, Stone (6th round , but basically a top 15 guy)
2022: TB (Stamkos, (plus unreal hits with Point, Kutch); COL (like EDM...speaks for itself, they're stacked with top ten pick talent)
If you don't sink to the bottom for a top 10-15 pick at some point in the team life-cycle its pretty hard to actually win the cup. The Bs played St Louis but that was after TB got upset by CLB and STL rode an absurd run from their goalie. Let's not forget that those teams above also have top 10 pick D-men too: Hedman, Makar, Ekblad, etc.
True differential scoring is just really hard to find outside the top 15.