Startups tend to be secretive. Some are secretive about their startup plan ('stealth mode'). Most are secretive about for example number of (active) users.
I wonder why that is. There are definitely more ideas floating around than capable entrepreneurs, which suggests that spilling the beans on your idea isn't a big risk. Being secretive about your statistics is even more confusing to me. Is there some sort of upside to valuation that I'm missing?
* If you're entering a competitive space --- and particularly if you have a direct sales model with medium-long sales cycle (ie, you sell to companies) --- your competitors can neutralize you without copying your features. All a company with a shipping product has to do is "roadmap" your features for you to lose competitive advantage.
* There's what Joel calls "The Marimba Effect". As long as you keep quiet about what you're doing, your failures and missteps don't count against you. Once you launch, prospects can start to form an opinion that's hard to shake off.
I can't say that these are dealbreakers if you're starting some social calendaring service for pets, or (like most YC'ers) considering some kind of social network code autoindentation product for MzSchemers. But we are not awash in examples of companies that opened up early, launched small, and went on to huge success.