This depends. For most startups what you say is true. You can launch 5 times and most wouldn't notice. But for a startup with a lot of press, a bad launch can hurt momentum (I'd think). Look at Color.
But, for the rest of us nobodies, there will be other opportunities for news and first impressions as we trudge along. I launched my first app in 2005 to no press, just a couple of blog posts. It was almost dead, then NY Times writes about it 3 months later while covering the topic (Personal Finance). Every few months a another press mention would popup out of the blue and 5 years later when it got its second NY Times coverage a whole new batch of people discovered it. Of course, I no longer own or work on it, and I'm still "working for the man" so what do I know?