You're leaving out the Vegas series collapse in 2022-23, where Jack Campbell had to come in and stop the bleeding, and played so much better than Stu that some people actually think he could've saved that series...
Even in the LA series, in 3 out of 5 games Stu had a save percentage in the .800s. In the only loss of the series, Stu had an .808...the team lost in OT. He had two great games, one OK game (Game 1: had a shitty .892 but faced 37 shots), and two poor ones (.857 and .808). When your team wins a game and your goalie has an .857, well...unless you're giving up a crazy amount of high-danger chances (and the Oilers were among the best at suppressing those), you probably have to drag your goalie to victory.
And glad you added "eventually" for the Florida series, because he was poor in the first three games...but Game 3 especially, which his cheerleading section conveniently ignores, saw him finish with an .826 while McDavid had two assists and the Oilers only lost by a single goal. You still have people on here dancing their way around that performance, but that's as clear a smoking gun as any that he was the team's single biggest reason for that loss.