I also think that the power creep started out with Gen4, as it had lots of legendaries and evos for older mons. (There's a literal god there dammit.) However I feel like power creep is a symptom of a deeper issue in the series: it's basically mass production, and for mass production you got a few cosmetic changes from gen to gen but almost no meaningful change in core gameplay. And eventually people like you, @sleepybisexual and me got tired of that "base" product.