I'm puzzled as to how startups grow to so many employees. For example, dropbox's core product hasn't changed much from inception. Why not hire a small core team of 10 engineers and focus on operating the main product?
There are additional risks with hiring more people... you need to find stuff for them to do, and you end up building things that aren't valuable. At worst, you make the product worse. Once you've found the main valuable idea that'll get you most of the value.
Quip has ~16 elite employees (Co-founder is ex-CTO of Facebook) (October 2014) (<a href="http://www.quora.com/How-many-engineers-work-at-Quip" rel="nofollow">http://www.quora.com/How-many-engineers-work-at-Quip</a>) and a great product used by many.