Things from YC never really were independent companies, I think it's more clear to view all of YC as one company. The separate entity thing is mostly a trick so they can book revenue to themselves as real revenue.

Look, we have 37 other YC companies paying for our product it's so popular and successful. Hits different if you view it as a single company, imagine AT&T promoting their internal customer service software, used by 37 divisions of AT&T it must be good!