Totally agreed. This is a bunch of rhetoric coming from someone who has no business telling other startups that what they're doing isn't important enough. Every word in that post is written with a hint of "At Asana we're doing amazing world-changing things, and your shitty startup isn't". And guess what, Asana isn't doing anything important either. Asana is adding social networking features to a chat app for business right in the middle of a Social Network bubble.
The reality is unless you're curing cancer, building a space station or cold fusion reactor, chances are you aren't doing anything all that significant in the long term history of mankind.
Mr. Rosenstein can come down off his high horse now.