The companies that get into YC are often speculative in their ideas. Maybe it is devaluing the idea over the execution. Maybe it is the belief that getting in early to a growing trend is more valuable than reinventing an existing idea.
Regardless, the result is great teams of founders who think the key to success is a crazy idea. Sometimes crazy ideas work (AirBnB was kinda nuts at the time) but there seems to be a heavy weight in companies funded towards those types of investments versus the ZenPayrolls. Which tends to attract the same.
* They were Switchboard Labs at the time, doing something totally different.