So, anything from the right should be a lie by default? Then google or whoever can just unrank the article to oblivion, since it statistically contains "lies" according to a biased majority? Do you see how dangerous this is?
You must surely know that many right-wing sources are notorious for lying, especially Breitbart and Infowars. Being a right-wing source shouldn't mean your lies get a free pass.
For some interesting information on how right-wing sources are obliged to lie or be rejected by their target audience, see http://uk.businessinsider.com/conservative-media-trump-drudg...
Bias can be dealt with by being an open system. People can see the algorithm, data input, and judge whether the output is fair. Independent audit and review of the system would be miles better than what we have now.
As far as bad-actors trying to game the system, that's another matter.
Having a rating system is just a tool. It will make life easier for every consumer of news.
Life with a spam filter is way better than no filter. We learned this in the 1990's after spending a decade writing them for email, when email became nearly useless as a tool because of spam.