I'm fascinated by this point.
This was/is one of the critiques of (Rap) Genius as well: hip as its authoritative voice was, it nonetheless moved toward the encyclopedia. Though the company has since pivoted to allow more individual commentary than encyclopedic exposition--I don't think they've quite worked this out in the UI yet--the original site, and the part I think that is still most compelling was the Wikipedia for rap lyrics.
But from a pedagogical perspective, that expository mode of analysis was really only one, and perhaps not even the most important, use of collaborative annotation. For my part, I allowed teachers to duplicate texts and create their own versions, instructing their students to annotate however thy wanted them to: authoritatively, discursively, inquisitively, with GIFs.