I think it's a useful heuristic, but if you apply it too harshly, you'll deprive yourself of interesting perspectives. It's also hard to correct, because you don't get to know how many false positives it produces. So, it should be used with care.

People may make mistakes in an area they have less expertise in than the reader, and still be able to provide a view from a side the reader knows less about. Also, it's not difficult enough to mistake a deviation from a dearly held belief for a faux-pas in somebody else's thinking.

You can argue that it's still worth it to apply the filter strictly, because there's so much chaff to cut through; but it's not always done with enough appreciation for how much it may tend to reinforce one's own bubble. I also suspect that the more trigger-happy people would not be too understanding or even introspective when having that same filter applied to them.

Having this filter is useful and necessary. It's just that when it can be observed, because the people applying it post about it, it often seems to be the overzealous kind of dismissal.