I'd argue there's no such thing as "transparent terms of use" that wouldn't be open to legal challenge. Twitter and facebook have terms of use, they're as transparent as any other site in that regard.

Reddit has banned whole sub-reddits and shadowbanned others, Hacker news has human mods who make qualitative decisions to curate conversations on this site.

This hits every forum, every newsgroup, every site that has user generated content.