This is the reaction caused by a minor Kickstarter that took inspiration from Dark Sun themes. Imagine if you will the complete meltdown that would occur if Dark Sun 5E was under development. The Dark Sun setting in 5E would be shibbolethed and litmus tested to death.
The result would be worse than just the heart of the Dark Sun setting being ripped out, but a modern iteration of book burning would take place, with 2E supplements like Slave Tribes being pulled from sale.
At best we will have a situation where WotC designers will insist that they “love the Dark Sun setting” while ripping the guts out of everything that makes the Dark Sun setting unique and different to the other fantasy settings.
So yes - I 100% concur with Dark Sun haters that Dark Sun should not be introduced in 5E. Let the benign neglect continue and keep the Eye of Sauron off our setting.