You're actually killing part of your virality, because part of how word-of-mouth works is when you hear about something offhand. You aren't always being direct

You're actually killing part of your virality, because part of how word-of-mouth works is when you hear about something offhand. You aren't always being directly pitched, and you don't always have a chance to press for specifics. For example, if a service is mentioned in someone's Twitter feed, or if I hear that one of my competitors, enemies, or heroes is using it, then I might have no idea what it is for and no better way of finding out than going to the home page. In that case what's standing between me and signing up is ignorance, and you're leaving that barrier in place. There's nobody out there so similar to me that it's worth my while to sign up for any web site they use, but there are a lot of people out there with enough taste and intelligence that if they use your service AND I'm interested in the same kind of service, then I'll sign up.