No, if there were serious, pervasive bias impacting scores, it would lower the correlation and MBFC would be an outlier in the group because they would be in agreement less. If something’s happening at such a low level that it doesn’t impact correlation, it’s just an outlier. Multiple researchers conclude that the differences between monitors is too low to impact downstream analysis which is hard to square with your claim. And, each entry represents about 0.01% of their content, so what percentage of that data is being used to draw sweeping conclusions about the whole?

There is just high agreement about what constitutes high and low quality news sites. The notion that MBFC is somehow inferior to other bias monitors or extremely biased is not supported by evidence. If one of those organizations is better than the others, it isn’t much better. As this study concludes, because the level of agreement between them is so high, it doesn’t really matter which one you use. They’re all fine. Even they think so. Not only do MBFC ratings correlate nearly perfectly with Newsguard, Newsguard’s rating of MBFC is a perfect score. They’re well-respected by each other.

And, really, how could these researchers who’ve dedicated their lives to understanding this stuff have gotten it so wrong? Academia definitely isn’t a hotbed of conservatism. Using awful tools could destroy their careers but MBFC is regularly used in research. Why? How are these studies getting through peer-review? How are they getting published? There are just too many failure points required.