Submitter here:

Briefly, the idea is to transfer the effort of reviewing documents to a crowd-sourced platform: a user provides feedback to other users' documents, and in return obtains feedback for his own documents.

My motivation stems from "yet another review" of a research paper of my own that I had already read many times for re-submission. At the time I was already so fed up of reading it that I'd rather read someone else's work instead, hoping that another person would instead read my own work. Not only would that be refreshing, not to be reading always the same thing and maybe learn something new, but it would also be way more productive to catch problems in the document with a fresh pair of eyes.