YC is not some end all be all arbiter of what will succeed. Plenty of YC startups have failed.

https://ycgraveyard.iamwillwang.com/

https://startups.rip/

This is a "Launch HN" / "YC P26" thread, so YC funded them.

If YC didn't fund this particular idea, they funded the team to pursue some earlier idea that the team then pivoted from to try this one.

In any case, the team needs to pivot. This idea is lighting cash (and time) on fire.