Any netnews set of servers not owned by cooperative entities is more supportive of free speech than any single-point-of-censorship/chokepoint like a website. If a website's owners don't want to carry one's posts, or if a sufficiently organized set of readers don't want others to read that post it's easy to score the post low and effectively keep others from reading it by default. Not so easy to do with netnews where servers share posts with each other; servers that share posts will typically spread that post to another server. There are multiple points at which one can upload the post and wait for the normal store-and-forward mechanism to work. That post can be scored low or marked read by an individual, but such action won't keep others from reading the post.

I think this is a big part of the reason why centralization is always censorship and, in turn, why organizations desire that power when setting up yet another discussion site.