There are some stuff in other setting. And these settings are mentioned very often.They do? Didn't someone say earlier that pretty much all official adventures (except Curse of Strahd) are set in FR? And how would we even tell these apart? Aren't they both the same sort of generic bland fantasy settings like
The point is new players and DMs will design based on what is pushed in the main books by WOTC.What that has to do with anything? Using halflings is not inherently any more difficult than using any other fantasy species
And WOTC is pushing weak settings for halflings.