Not at all a vocal minority and being this dismissive of genuine complaints people have had for over half a decade is so painfully disingenuous that I don't even know where to begin.
All that has happened with content in Dawntrail is that it is designed with the expectation that people will know basic underlying game mechanics that veteran players have been more exposed to.
It's a wake-up call to actually learn the underlying mechanics of the combat system, rather than coasting on by like people have for years. Yet all everyone does is complain about incredibly easy mechanics that would be easily resolvable if they actually bothered to ever learn what a snapshot is, or weren't allergic to stepping into the animation of an AoE, because they fail to understand that the animation and VFX are safe so long as the marker is gone as you've resolved the mechanic.
What we are witnessing is not "Hardcore casuals" changing the game, but rather a gross, widespread lack of basic, formerly common game logic and knowledge that was bred into the player base from how utterly lackluster content was in late Stormblood, and the whole of both Shadowbringers and Endwalker. Learn how to actually play the game you all claim to love and to accept that you have to learn a fight to clear it.
Alexander 12 took me ten attempts day one because back then people actually had to learn content to clear, and you know what? That was considered casual content back then by everyone who did it.
Nothing has changed other than the average casual's expectations of what they will have to do to clear content and get their dopamine rush, its time to get good at the game again and quite complaining.
All this time and energy spent moaning on the forums could be put into going into duties, learning mechanics, how the battle system actually works and getting better enough at the game to not be a burden to everyone around you. Slapping labels on people doesn't benefit anyone and only fans the flames of discourse and dissent.