It is in their wheelhouse, but this information is probably deemed to be part of the "secret sauce" which would be hard for any "information economy" company to part with.
Agreed. That said, I think sharing a "top 50" list would be helpful to the community + encourage good behavior for investors who want to get on the list, but at the same time the full list would be even more valuable and would be proprietary to YC and its alumni.