I agree that goalies who get hot usually go on deep runs, but how do you predict which goalie will get hot? There's incredible variability in the performances of goaltenders, as we have seen with Braden Holtby over the years. Ever during his prime he laid some eggs in the postseason, and during his downswing he had a very good postseason. And he had a few average years in there as well.
Same with someone like Vasilevskiy who is touted as the best in the business right now, but he was dreadful in 2019 when they were swept by Columbus. Jonathan Quick was good for two postseasons but beside that has been a below replacement level goaltender for much of the time. MAF went from #1 pick to sub-replacement level to godlike to average. Jordan Binnington was solid and now is a complete wild card. Carey Price went from elite and commanding an $84 million contract to a backup. Tim Thomas inexplicably had the single best season that I can remember, then he went to hide in his doomsday bunker after he became bad. Mike Smith went from decent to a complete joke and now he's pretty good again? Bobrovsky won the Vezina then was really bad and then rebounded a bit.
There's no consistency at all. Obviously you need someone with baseline NHL level goaltending skills to be competitive. So if you want to argue that neither Vanecek nor Samsonov have baseline NHL goaltending skills then I guess that's fine, though the numbers really don't support that. Ilya Samsonov has posted better numbers than John Gibson in the past two seasons and Gibson is pretty highly thought of. And he has some similar numbers to Tristan Jarry who I guess is now good and capable? Also pretty similar to Marc-Andre Fleury who was recent in Vezina contention.
Edit:
Why Goaltending is Basically Random and Will Always Make You Look Stupid (In 5 Graphs) is a good primer on the randomness of goaltending.