While I never experienced this directly, when the business eventually transitioned from the founders stage to control by investors ... some employees felt a bit of that great early vision was lost that made the environment so amazing.
Unhealthy competition between managers vying for positions of importance crept in a bit.
Hope it wasn't true. Still think they have a great product, and many good people...just not as great of an environment as their early days. Of course, that's the hard part about large growth anyway.