For my 2 cents on this - I don't think we should ever censor anyones right to comment, however as a READER I would like to filter based on some criteria.
E.g. I'd like an option that lets me only see the average rating based on people who have completed it, the average rating based on people who have NOT completed it, and the percentage split of a show complete vs non complete.
With that data - I can see whether it's commonly dropped (or commonly completed) - if 80% of people completed it vs 80% of people dropping it, you can immediately tell *something* about the show and how people reacted to it. I can then read the comments on those that kept up with it as well as those that didn't, clearly by separating them out.
I do the same on Amazon - i'll click on the 4-5 star ratings and see what people who liked it said, and then the 1-2 star ratings and see what turned people off - and see if any of those feel like things that gel with me.
What that does is put the power of choice in the readers control, without censoring the right to review and comment from anyone - which feels like ultimately it would do what everyone wants here?