Sadly, what inevitably happens is these players rocket through the now-nerfed content only to hit the same exact walls with the current content, become frustrated, and leave again until the whole cycle repeats itself.
This is so true, well also goes for the once that eat the new content for breakfast. And since new games ATM gives away gear more quickly, none have anything to do.

It's why newer games never see a stable server population any longer. You see a spike after patch/expansion, then a fast dive, then up after next and so on.

Also, you got to look at the long term. Without things to help new players, they can never catch up. In addition, it'll leave a big gap between the "hardcore" crowd and "casual" crowd where it becomes hard to provide consistent content for both. If they followed the traditional style of building harder raids that only the top players can clear, people will eventually leave cause they aren't getting anywhere in the game.
I guess I can see your point since this is such a vertically progression kind of game. Might not agree fully with it, but can see it.

I still think at least they should have taken longer to nerf it so hard. Sort of like nerfing it so it was at a range between casual and hardcore, something for those people in the middle. And after each patch, they move up a slot. That way you would also have more "current" content being played since you have 3 tiers of players.