No, I'm realistic. Very often my meetings with VCs start with "How many users can you get?". They don't care about the product per se, they care about registered users, because the more users, the easier it is to sell the product at a good price. Yes, I prefer services without registration, too. No, these usually don't last long. That's reality.
Thanks for the VC 101 lecture, but OP might not be looking for VC money and it's hardly an expensive service to run with the current limit of 5 users per IP.
If you actually look through the site, OP mentions plans to add an accounts system soon for power users.
We don't know what kind of plans OP has for seashells. With a healthy base of power users, and no board of VC investors trying to milk it for all it's worth, a concurrent service that doesn't need registration is entirely plausible. That's reality.
My comment didn't refer to seashells in particular, but no-registration services the parent mentioned. Once the service becomes really popular, it usually either breaks or the owner realizes they need to do something to at least cover the costs of running. true, this could never happen to seashells as the service is quite specialized.