Bloomberg TV (which also owns Business Week) covered this a month ago in an interview with Paul Graham: http://ycuniverse.com/pg-on-bloomberg-tv

As was said at the time, the portfolio effect requires investing in many startups to diversify risk. Most startups are high-risk investments that will obviously fail. And only extremely qualified investors should invest in startups.

One major issues with all these accelerators is the mentors are increasingly less qualified and experienced to give advice. The other major issue is the startups themselves are not focusing on actually making anything people want, but rather focusing on raising money. Paul Graham said as much at Demo Day for YCS12, where the startups were prohibited from speaking about fundraising efforts: http://ycuniverse.com/ycw13-likely-less-than-50-companies