It seems like a standard practice on HN nowadays. I am afraid some mods may be politically charged. See the following thread for example https://news.ycombinator.com/item?id=42716926

dang is about as politically neutral as it gets, but it's become very apparent that anything that points to something negative that may loosely relate to Conservatives or the Republican party will get flagged by users.

Do you really need to ask?

Sad to see it getting flagged here, especially since it’s a story about hiding what people see.

Folks who believe their feelings trump facts