It's all about incentives. Plug and Play's business model is people paying for office space. So, they take anybody who comes and is willing to pay their prices for real estate, and they try to call investors in so that the people paying for office space can present to them.

Investors want to see a bunch of qualified, filtered startups. So, the incubators/accelerators that provide "good deal flow" for the investors have the best reputations with the investment community. Plug and Play doesn't provide that.