This would devalue the signal of YC accepting a company, and inflate the value of the signal of a YC partner investing in company. In fact, not having both coul

This would devalue the signal of YC accepting a company, and inflate the value of the signal of a YC partner investing in company. In fact, not having both could be a negative signal, at which point YC is poisoning itself. This also leads to YC subsidizing one of their partners, and works against its best interests. YC's goal here is not to maximize efficiency of the market as a whole, it is doing this for self-preservation. Aside from that, if PG feels that the signal is overvalued, the remainder of his own portfolio becomes toxic unnecessarily. So it's a bad outcome if the signal is accurate, and a worse outcome if it isn't.