Yeah i got you're point even the rating of course are weird Last Day i take a course on content marketing from coursera, the course is well rated but when i 've gone deeper in that course i was more and more bored. In order to know if it was my fault or just my opinion i share it with People so they could try it, those People come back to me saying it was a nightmare (the content is good but the instructor isn't engaging etc)
I think it could benefit both side to have something like that, because first you make decision clearer for student and second you could help platform to put certificate only for courses that worth it.
Third point:It could also benefit university to cleraly know that course they should put with a certificate and which course they should really put on mooc. Let's calrify it, for exemple Harvard put some free courses on Harvard website, some of these courses are way better than those they proposed on coursera etc.
Last point there is a lot of platform, a lot of them are talking about how they're certificate is cool, the fact is that you don't really know if employers really value those certificates.
If you need some help let me know Tina.
It would take much time to build a website for this.