There are plenty of successful YC companies that wouldn't register on Google's financials and would probably be shut down/ignored by Google if they owned them though. Obviously YC would like all their portfolio companies to be massive but I don't think they force companies to shut down if they don't become Google massive.
Not YC itself, but other investors that have an actual board seat and invested more than 125k likely have a vested interest in seeking a lucrative acquisition.
By that kind of judgement, this forum should be just fund raising? No more open source or tech heavy articles?
A lot of us who are in this forum are here for the "news", not for the "ycombinator".