WotC only published the [Dragonlance] campaign setting, the rest are [...] licensed.
[+1]
A.K.A. second-party?
Yes, but fully legal as far as WotC is concerned.
Whereas third-party is not, since they don't get any money
You could find a third-party source to do just about anything now-a-days.
Ex: Halfling Chicken Wrangler to an infernal feat called "Wish" in an AEG book I bought a long time ago