So on the high end a SC Winning goaltender might expect 750 shots (though generally less) with that in mind Mike Smith's 0.913 and Connor Hellebuyck (the person I see you advocate most strongly for) has a career playoff sv% of 0.916 in a full SC run that represents ~2 more saves from Hellebuyck. FYI Campbell's career playoff sv% is 0.920 (18 game sample size).
Lets say we get a 0.925 sv% the kind of performance no one complains about, that would be roughly 9 more saves over the course of a SC playoff run than what Mike Smith gave us. Just looking at Ceci's playoff numbers this year, the effect of upgrading him to a top pairing defender should be at minimum a 12 goal differential improvement over a full SC run.
Elite goaltending is a great aid and a strong moral booster for an SC run, but at the end of the day all that really matters is goal differential and every other position has less variability in performance level from year to year. The elite goalies you like are more likely to put up elite performances then other non-elite goalies, but it isn't a certainty just a higher probability any goalie can get hot or cold.
Elite goaltending is 100% not a requirement to win a Stanley cup and you downplaying every example of that is just romanticizing teams because they won a Stanley Cup. Watching Vegas and FLA neither really impress me and neither seem beyond what we are capable of, it's not like COL last year who was a clear cut above us, this season I think nothing more than an upgrade on Ceci or a 0.910 sv% goalie would of probably been enough to win it all.
Show me a team that had average-ish goaltending AND a weaker blueline akin to the Oilers (as in no no.1 D) that's won a Cup in the last 20+ years. Forwards, d-corps, goaltending ... you can be weaker-ish in one area, but not 2/3 if you want to win a Cup.
Carolina had an OK blue line (not that great), but Cam Ward was great in the playoffs for them in 2006 and their forwards were good/deep.
It's very hard, bordering on impossible to win when you have no dimension to your team other than "have 4 forwards beat you by outscoring you, preferably with a boat load of PP chances".
You need to either have a no.1 D who can control a game and win some games that way (which we don't have) OR a goalie who can win you games here and there during a playoff run even when Connor and Leon don't have a great night. A guy in net who can elevate their play to that level.
We don't have either right now. McDavid/Drai are great, but they are not *that* much better than Crosby/Malkin, MacKinnon/Rantanen, Ovechkin/Backstrom/Kuzentsov that you can sit there and say "well, you don't really need either the goaltending and we'll just give you an OK d-corps and we expect you to win".
Like it's an unreasonable ask. Those other duos/trios have way better run support, we are asking these two guys to do way too much. You can't win 16 games in the playoffs with 2 players basically be asked to win every f***ing game and the back end and goaltending situation being just "alright". Your goaltending or your D needs to win several of those games in the playoffs even on nights when no.1/no.2 offensive guys simply don't have it that night or aren't getting the bounces.
The most wins the Oilers have got in a playoffs in McDrai era is 8 wins ... that's still a Red Deer to Edmonton walk away from the 16 you need. To get to 16, there needs to be other players specifically in the defensive and goaltending position that chip in with a win here or there.
Crosby/Malkin/Kessel won with not such great blue lines at times (good low event guys though) but with good goaltending. Colorado won with poor goaltending last year due to Kuemper's injury, but it didn't matter because their blue line was elite to go help their forward group. We didn't get lucky with a bonafied no.1 D, we need a goalie to win and even steal us some games in the playoffs, not just be along for the ride.