A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
It's always been there: business, leisure, other are the choices.
I would guess that the purpose is to gather more (big) data for Marriott's analytics regarding rate versus number of rooms reserved, etc.
In other words, it's none of their business (but that's not a choice for boxes to check).