YC.org literally backed OpenAI in 2015, Cruise a year before that, and ScaleAI a year after that.
Per YC's publicly available records, the earliest they funded a ML/AI business was in 2008. They aren't late, but this AI specific Early Decision may be in reaction to funds like AIGrant.org, SouthParkCommons, Neo et al.
Exactly, the chances of getting funding for AI companies are up considerably and if YC doesn't fund them someone else will. To get a seat at the table they need to move faster compared to their normal schedule.