The important part is that they are going to annotate those first-party sources with 'fact checking', which is slanted left [0][1] in the US and has infinite regression problems. Also, they are doing this all with humans, and the overt perception of bias means that it will attract biased people over time.

It may eventually become an attack site that cherry-picks the past to provide ammunition, because that is a lower energy state, being easier to do than actual human annotation.

[0] http://thefederalist.com/2016/12/16/running-data-politifact-...

[1] https://thefederalist.com/2016/12/29/politifact-slants-truth...