See, that's the kind of thing I'd like to avoid; see:
@Remathilis's post above. Because once you set that at the baseline, where do you stop? Do Clerics still make sense in a world without deities? What about literally every spell that would make life on Athas (or its off-brand equivalent) substantially better?
I'm not saying that I don't think it's possible to make a Dark Sun or inspired setting utilizing
everything in the PHB (<side-eyes
create or destroy water, a 1st level spell), but it would be significantly easier (and less disappointing to the
@Remathilis's of the world) to have your own list of species/heritages/classes/spells (borrowed or not from the OGL) rather than handing them a list of what's forbidden.