This is also a cautionary lesson for founders about raising at inflated valuations--Genius's series B raise at close to a $1B post-money val will make it more difficult for them to exit with an acquisition.
(In fairness, they completed that round with the intent of "annotating the internet", not becoming the music content platform they've since pivoted to.)
See Ben Horowitz's note: https://a16z.com/2014/07/11/from-rap-genius-to-genius-2/
Marc Andreessen's note: https://genius.com/1102682
I think it may be because at it's heart Genius feels to me like a skinned/specialized Wikipedia, and Wikipedia already has other information covered. Lyrics are a good fit, because Genius has a format that suits itself well to annotating lyrics, and it is a reliable source for quality lyric content. So many lyrics sites other than Genius are horrible to look at and usually are riddled with ads and popups.