We also got out-depthed in the Winnipeg series. Abundantly clear when you shutdown McDrai, it makes the job significantly easier. Heck of a lot more went down in the Chicago series, too than just goaltending. Larsson getting hurt and Bear losing Cinderella's slipper definitely didn't help.
Goaltending plays a big part, which is why it shouldn't be ignored. But you could have prime Brodeur. If your roster in front is turning the puck over frequently, giving up five-bell chances left and right, they're still gonna lose.
Improve the team up front and you won't need a Vezina calibre starter between the pipes.
In the Winnipeg series the Oilers didn't give the Jets much in the first two games, Helleybuck was simply one save better, in the 3rd game they shit the bed after getting up 4-1, which is something that goes back to the 2017 playoffs even (collapsed against the Ducks multiple times).
4th game is kinda a who cares by that point, you're not coming back from 0-3 down, but Helleybuck again made 1 extra save over Smith anyway.
This team just expects to lose when the goalie is not standing on their head. You can see it also whenever Koskinen is in net, the whole team shrinks and slumps any time a goal is scored. They don't have the maturity/confidence to overcome a situation where the goalie on the other side of the rink is playing better than their guy. Which stems from not having enough talent, they know only 2 guys can do anything offensively and if the other team won't oblige them and play a somewhat loose game, it becomes very hard.