YC or any successful VC doesn't fund ideas. There is something else the founders have figured out which is key to success and funding. This could be a distribution trick, a key insight, a user growth metric.

Its not hard to imagine YC or a VC coming across the same idea pitched by different founders. Why they picked the team they picked cannot be obvious from trawling the startup directory, that insight is hidden, its literally a secret that should be guarded