That's exactly what page rank was about to begin with. However... 1. Various 'credible' news sources also link to dodgy sites and articles, either when critic

That's exactly what page rank was about to begin with. However... 1. Various 'credible' news sources also link to dodgy sites and articles, either when criticising it, posting a story said sites first ran or simply because they've fallen for 'fake news'. 2. A lot of trust signals are easily gamed, like .edu links going for a fortune on SEO forums. 3. At some point, quantity will probably win out over quality.