While this rating for Steem was good publicity to get the word out to a wider audience and generate more interest in Steemit, I wouldn't place much importance on Weiss ratings based on their flimsy methodology. They may know something about stocks but they're clueless about crypto currency. Giving Bitcoin a C+ is some kind of joke, and Cardano a B- when they don't even have a working project, just a token and a bunch of academics with big ideas. This is nice for Steem but from an investment point of view, take this which a pinch of salt.