Y Combinator has many characteristics of a cult; a Dear Leader (who appoints his successor himself!); a devout following of young people who are ready to make great sacrifices just to be part of it; mega-churches and mass events such as Startup School; dubious characters as spokesmen (Andrew Mason, Travis Kalanick); apologists who contemplated a career as priest (patio11).
They prefer young people because bullshit is harder to swallow the older you get -- and if your bullshit detector is hyper sensitive, like Colin Percival or Maciej Ceglowski, you either can't tolerate the thing (Maciej) or you feel like it leaves you cold (Colin).
But it's also an extremely successful cult --possibly one of the most successful ones ever?-- so who are we to criticize.