Makes me think, maybe it's time to create a "bootstrapped" badge, or something like that; something that sites that didn't take VC money could proudly display? At least for me personally, whether something is an investor startup or not is an important data point for deciding whether to invest my time in it.
www.hellolyra.com
Hasn't been updated in a while though.
I mean, the K-factor is either greater than 1 or it's less than 1. If it's less than 1, you can have 100s of years go by without gaining a meaningful audience. If it's greater than 1, then they would have seen that in their retention/cohort/signup analysis. Even, if only a sub-segment of their users were growing at a >1 K-factor, they would not have shut down. Since their shutting down, that's clearly not the case.