It pops up all the time, it’s a waste of time and I’m sure it has been used countless of times to discard some piece of information. It doesn’t add up anything productive to the comments, people who comment don’t even say anything they actually think they just “did you know that MBFC says this so it has to be truth?” I could go on but I think you get the idea.
I think the issue is that to a general audience it’s something that you can’t just say in passing with a noun phrase without establishing that you’re talking about this bias first, but if I had to produce a phrase then it would probably be “the less-politically-educated” or something, since obviously there are lots of people with political education who are contributing to problems in The Discourse, but the people who just hold up MBFC like it’s a cross to repel the vampire of radicalism are, in my opinion, mostly the kind of people who have very little political education and just consume a lot of corporate news or NYT (or some equivalent). The ones with an education will more consistently present (hackneyed) arguments or actual articles.
I could be wrong though, it’s just the impression I get.