Source? Those are pretty serious accusations.

Personal anecdote.

Vox itself removed comments after a time, probably because this bubble could not reasonably be preserved in response to the majority of their articles.

The Verge is somewhat more open, depending on the topic and whether it is technical or political in nature.

Polygon's Ben Kuchera is a caustically aggressive moderator, and is the primary one I saw behaving in this manner, in addition to antagonizing commenters who disagreed with an article's premise; doubly so if he himself wrote the article.

Funny, I don't see these as accusations, I see these as curated engagement.

The upside is there, if you know up-front its the basis of the engagement. If its applied retrospectively it sucks, for a number of people.

But curation is not always bad. "it depends"

There's no "engagement." It just ends up with banal "I agree" posts that add nothing to the article. And it doesn't add many to them, Polygon's comment sections tend to be tiny and not worth reading, for example. You get better news and engagement on reddit.

They used to be larger, and I believe that restrictive, inconsistent moderation drove people away, but that's merely a guess of one probable cause.

Isn’t this what Vox and friends already do, just with s/alt-right/leftism/ ?

I believe that is their point.