Bobby Hull and the Blackhawks only won 1. Orr's Bruins only 2. If it was so easy for Chicago and Boston to win Cups left and right, then why did they win so few?
Between 2009–2017, a nine year stretch, 4 different teams won the Cup (CHI 3, PIT 3, LAK 2, BOS 1).
Between 1995–2003, a nine year stretch, 4 different teams won the Cup (DET 3, NJD 3, COL 2, DAL 1)
And both Boston and Dallas, the teams with a single Cup among those groups, also made another finals appearances during the respective timeframes. I think you're fooling yourself if you believe 30 (or 31 now) teams are plausible challengers for the Stanley Cup any given year. 30 (or 31) teams aren't. Cinderella runs always seems to end in the finals, for some reason (VAN 94, North Stars 91, FLA 96, CGY 04, CAR 02, EDM 06, etc.)
If we go further back in time, we have Pittsburgh back-to-back titles in the early 90s (with Boston making two finals between 1988 and 1990) and then in the 80s two dynasties (NYI and EDM) and three challenging teams (PHI, CGY, MTL) either making the finals (Flyers thrice) or winning a Cup (Calgary/Montreal). So what it seems to boil down to each season, pretty much in any given era (say a 10 year period), is 6 or so plausible winners but only 3 or 4 teams really making it.
Tell Aleksandr Barkov it's easier to win a Cup in a league with 30–31 teams. Or Joe Thornton. Or Iginla. Or the Sedins. Or Lindros. Or Bure. Or Lafontaine. Or Sundin. Or Turgeon. Or Roenick.
It's not a given conclusion that the width of elite talent expands just because the number of teams do so. And even if it does, some teams will be more stacked than others.