Where am I saying that Evenepoel, or anyone else for that matter, is "brilliant or ***"? It's the W/kg numbers that make it seem that he and his closer competitors put in brilliant performances, I'm the one who's being more restrained by saying it was a good-but-not-stratospheric performance, and one that was the best he's done in a while - so I'm literally taking it as a sign his climbing is improving.
Regarding Vine, there are very few people who can put out Pogacar-tier numbers even for one climb. Of course that doesn't automatically translate to being a GT winner, but if you think that Vine is one of those people his odds of going on to be one will be better than what the bookmakers will give you. Also the Pogacar data include a number of smaller races, they're broadly in line with his GT numbers anyway. No, it's not the same as doing it in a GT, but it's about whether or not he's showing the potential to do so. Either you take the numbers at face value and say he showed the potential to compete with Pogacar (and therefore that Evenepoel showed the potential to beat Pogacar), or you take the numbers at face value but say they have little predictive power (and therefore that Evenepoel's performance today doesn't mean that much), or you don't take the numbers at face value (and therefore don't take Evenepoel's either, because if Vine did 6.3 W/kg then 6.5 W/kg seems a good estimate for Evenepoel's performance) and say that he didn't show the potential to compete with Pogacar (and therefore that Evenepoel didn't show the potential to beat Pogacar).
I address most of this above, but the way I see it, either the calculations are off and we lack the context for Vine's power data, or Vine's power meter is off and he wasn't as good as his data suggests, or both are true, or neither are off and Vine really was world-class today. I think the former is the most likely and therefore the numbers that are being thrown around upthread aren't meaningful.
And if the argument is that you can't compare numbers here to those in GTs (which is fair), then there isn't much point in reading much into them in the first place.
Tl;dr - power numbers aren't that helpful.