I like the idea of annotation and I even sort of like Genius's implementation of annotation. There's a pretty decent annotation of Gatsby on the site. Virtually every line of The Waste Land has a good annotation there too. But, not to put too fine a point on it, this stuff all seems like, from a platform perspective, something Dustin Curtis could have built solo.
It's just that annotations, by themselves, fail to do that. Their VCs must've been betting either on some new killer feature that would come out, or that users would react to the existing annotation product differently than they did. For a VC, though, "could rival Facebook" is often more important than "has a small chance of doing so".
And that annotations could eventually be the successor to eg Disqus across the web, as well a new type of social network.
I think the world's information would be so much richer if it had played out. I'm still bullish on annotation tools for empowering knowledge.
But the annotations community outside of rap songs didn't take off in the same way.
Their only other major play is annotating things like scientific papers but I cant see the market for that being big enough to make money.