Boring possibility: the DM thinks halflings and gnomes are largely redundant, and picked one to ban.
Or the one shot involves outsiders getting involved with a halfling community in trouble!
The entire party showed up all using Zee Bashew’s lucky halfling diviner build and called themselves the Fellowship of the Rng
I mean, my best guess? Like chaotic neutral, players who “must” play halflings do it because they want to play to type… a very, very annoying type that doesn’t make for a fun time at the table… and saying this weeds them out.
Kender, who were similar to halflings and I think are now a variant, were notorious for this. Their schtick is that they “borrow” things from their party members, not understanding that it’s theft. It gave assholes license to be assholes under the guise of roleplay, until the table inevitably needs a talk.
Yeah, they were one of the true things I hated about the dragon books. When one of the characters went back and time and discovered that kender were straight up banned from the ‘supposedly good city’ (oh how shocking) and was horrified, I just rolled my eyes. If even the author, with carte blanche to write whatever and however they wanted, couldn’t make the habit cute, it’s never going to happen at a playing table.
Fun fact earth used to have Halflings until god band them
War crimes, Jerry
DM plans to use a fumble chart and he’ll be damned if any players are getting out of a nat 1 easy by playing halfling
Darksun during the Cleansing Wars?