You continue to use wild hyperbolae with your anti-Dark Sun propaganda. I'm beginning to think Dark Sun must have run over your dog or something! I don't like Waterdeep, but I'm not saying it should be nuked out of existence so no one else can use the setting. I just won't be buying the books.
The truth is Dark Sun was far closer to the core D&D rules of the time than 5e (Warlocks, Dragonborn, non-Vancian magic), so if Dark Sun shouldn't be called D&D, 5e has no right to the name either.
Sure, it has some tweaks, but that's the thing: THERE IS NO POINT IN PUBLISHING A CAMPAIGN SETTING THAT ISN'T DIFFERENT.
And Dark Sun goes back to one of the core inspirations of D&D - the lurid pulp fiction of the 1910s-1950s, especially Robert E. Howard and Edgar Rice Burroughs (check out the 1st edition DMG). This is something that was there at the start but has been lost over the years.
Dark Sun is the only one of the classic WORLDS OF D&D that repeatedly breaks the game's assumptions. Take a look at the other Non-Realm's settings mentioned in the DMG for a minute:
There is no reason why Oerth could not support everything found in the Core books. It handled everything 3e could throw at it and made it work. Mystara similarly has no strong prohibitions on what is or isn't allowed; a 5e conversion could fit everything into it just fine. Dragonlance during 3e found room for every option but half-orcs (and halflings, but kender are just extreme halflings anyways these days) so I don't see why that would be different in 5e. Ravenloft did the exact same thing in 3e; finding room for everything but half-orcs (poor half-orcs) but replacing them with a similar race called Calliban. Birthright hasn't seen formal update since 2e, but based on the limited amount I know if it, PCs had no restrictions and I'm not sure there would be any needed in 5e. Eberron famously declared "if it exists in D&D, it exists in Eberron" and between the 3e and 4e versions found homes for most everything in the core books. Planescape and Spelljammer can literally pull from anywhere. Nobody claims these settings are the same, but each takes the core elements of the game and puts their own spin on them.
So far, every setting in D&D so far has managed to adapt the the current edition, or has the potential to, into the setting. And then their's Dark Sun. Dark Sun has tried; once by Paizo in 3.5 and again by WotC during 4e, to drag Athas kicking and screaming into the modern ruleset of the time. Paizo found room for everything but half-orcs (man, they need a better agent!) and all the classes in the PHB and XPH (even paladins). 4e made room for arcane bards, tieflings, warlocks, dragonborn, and a lot of other Core rules options. And in both cases, hardcore fans have had issues with "ruining the setting" by trying to make it agree with the most recent edition of D&D rules. Dark Sun has been the biggest problem because, unlike every other setting, fans cannot accept it moving beyond the 2e box set assumptions. Which keeps putting it as the sore thumb sticking out. Every other setting can play nice with Planescape if you want it to; Dark Sun doesn't. Every other setting can absorb a new supplement and use much if not all of its options; Dark Sun cannot. Every other setting uses the PHB with minimal adaptation, Dark Sun doesn't. Every other setting expands the potential options for players, Dark Sun shrinks them.
At a certain point, the fact that Dark Sun has such a hard time doing what every other major D&D setting has, it starts to look like an issue with the setting itself.
It doesn't need to, of course. Primeval Thule has much of that Conan-pulp world feel with few if any changes to the core rules. DS 3e and 4e (as stated) has shown Athas doesn't break with including spellcasting bards or paladins. Its the dogmatic adherence to the 2e assumptions must be preserved at all costs that sinks the ship. If Dark Sun can adapt to 5e and use the Core rules like every other D&D setting does, I welcome it with open arms. But if the setting MUST be one that cannot abide monks, tieflings, or anything else that has been part of Core D&D since 2000, then maybe its best served spun off into its own thing.