They were missing two, directly related things: a revenue model and paying customers. (Not meant to be snarky or to point out the obvious, but simply factual.)
Worst case you're out a few hundred bucks for the company formation, best case you start making money.
Or it would take much more time than allowed, even with some outside funding?
For sure, I find the site is really, really beautiful and polished for a bootstrapped venture. It could maybe have helped to have something less polished but focusing on selling subscriptions earlier on? (no sarcasm really here, real question).
If one of the founders is reading, as a bootstrapper myself, I'd love to hear more about the underlying reasons to close.