It's actually a bad thing. Just like cryto all the YC companies sell to each other. As per their 2022 stats, more than 50% of sales for all YC startups are other YC companies.
So this is just a game of hot potato until they get a fat valuation, raise a zillion dollar series and then list it on the stock market for the retail traders to hold their bags.
Less YC startups= less customers for other YC startups.