Azzy
ᚳᚣᚾᛖᚹᚢᛚᚠ (He/Him)
I mean... there are quite a few options in the books outside of PHB that assume the Realms or at least previous Realms Lore/publishings:
I guess you could argue that those were in a Realm's Specific book, and that's true. But it was also the first supplement published I think.
- Uthgardt tribes (background & lore)
- Bladesinger (wizard school)
- Battleragers (barbarian path)
- Waterdhavian Noble (background)
- Faction Agent (background)
So, Realms-specific options were presented in a Realms-specific campaign guide. Most telling.

Also, neither baladesingers or battleragers (IIRC) are Realms-specific (they appeared in the Complete Book of Elves/Dwarves, respectively).
- The Seldarine from Mordenkainen's is a FR specific concept/name for the elven gods.
I don't know about that, it's been used in other settings. I can't remember if it was used in the original Roger Moore article that introduced the elven gods (other than Correlon, who originates in Deities & Demigods), which was a setting-nonspecific article.