I personally make use of Planescape and Spelljammer for all my D&D campaigns, just how prevalent those setting details are varies wildly. In the case of Dark Sun those details are very rarely seen, but genies would be a distinct example when I do have a bit of Planescape in my Dark Sun.
Athas and its crystal sphere is one that I depict very few beings knowing anything about and when they do it is often with dread as a barren, dead realm from which entrance is deadly and escape impossible. Elementals often know better, but I depict most elemental beings that have anything to do with Athas as being relatively “niche”. Athas is a rather obscure crystal sphere that even elemental planar travel/divination has trouble with, so it makes sense to me that a lot of the elementals we’d see dealing with Athas are the sorts who have some reason to avoid attention by the most of their kin.
This opens the floodgates in my mind for how to depict Athasian elementals, genies included. They might be exiles or fugities. Perhaps they just wanted to form their own petty kingdom or are maintaining a dwindled culture that most other elementals have moved past. Or maybe these elementals wish to take a crack at being worshiped and ascend to the ranks of the elemental lords. Either way this offers more than enough justification for me to depict genies as far more primal beings with a stronger spark of the divine. I very much like to depict Athasian genies in the style of Babylonian and Sumerian deities, uncaring forces of nature that promise immense rewards or guaranteed doom.
Edit: As an aside, if you are depicting any elemental clerics as creating their own faith around an elemental being or false god, genies are perfect as either that deity’s “angels” or as the deity itself.