Guess not. What about Friendster, or Facebook or MySpace?
None whatsoever. Yet they are all successful.
If your product isn't good to be spread by mouth of word, it ain't good enough to be socially viral.
I think one of the key markers for a new-economy startup is that it must be so good that word-of-mouth recommendation is the one thing that will differentiate the winners from the losers.
If people don't want to recommend it, tweak and reinvent the product until it becomes so good that people will.
Impressing investors is good, and necessary to get initial funding. But the key indicator of your success is whether people like it.
I've been in a couple of startups and seen too much from the Internet bubble days seeing people spend millions of dollars on advertising down the drain.
The new economy's rules are different and so are the marketing methods.