>>46072689XY was the descent but I think if any game needed a 3rd edition it would be XY. I think a lot of us chalked it up to a rough transition to 3D, which was definitely a factor but for all it's faults XY does a lot of things well and has one of the best new gen pokemon IMO. Unfortunately it also suffers from many extremes in the opposite direction such as the nonexistent post-game but as a starting point for a 3D mainline game and giving it's own region, trainers and pokemon a core identity that was appealing XY did very well even if it was a step down to get the next step up.
Where it all went to shit was ORAS not having anywhere near the same excuses that XY had and SuMo feeling like a step down from even that. I personally think the crux of the issue is that Gen V's reception followed by XY's reception absolutely broke Masuda, which is why GF doesn't even try anymore. That ORAS interview with him is just depressing, the man is a hollow husk of his former self.
But yeah XY isn't the problem, it's just the notable line before the decline.