In very early stages, profitability is not the best predictor of a future large liquidity event (i.e. the thing YC wants to optimize for). Facebook and Google would been thusly rejected.
I'm curious what the months-to-profitability was at Google. They were incorporated in September 1998, and turned a $7m annual profit in 2001. Were they profitable in 2000? 1999? They don't give data going back before 2001 in their own reports (http://investor.google.com/financial/2003/tables.html has 2001-2003).
I remember a gap between when I started using Google and when ads appeared on the site. Also, it's somewhat relevant that Brin started working towards what would become Google in 1996.
I was referring to PG's post above. He said that YC has a good idea of who is successful at the next stage after YC (the number who are either able to raise more after YC, or don't need to because they're profitable). If more and more YC applicants are profitable on the way in, the number who are profitable as they exit YC (one of PG's definitions of success as described above) will necessarily trend up.
