Also, no blue or purple Tieflings

But then we all know that the Player’s Handbook, p.42 disagrees… as does the Sword Coast Adventurer’s guide, p. 118 for the not so small fraction playing in Faerûn or some world derived from it.

This is entirely up to each DM and their players. DnD was never meant to have a codified set of rules. I’ve always taken them as advice.