My favorite long-term shared-post-and-comments site - far and away the most friendly and community-like - does not have downvotes. You can only 'favorite' a user comment. If your comment is not 'favorited' it is also not slapped with a downvote. (I find downvotes to be counterproductive and often arbitrary if not malicious. And one sows another.)

Moderators decide only what posts are productive. A dozen or so a day result. No topic is too 'far out' or rarified. The posts themselves may also be heavily-favorited, but almost always are at least lightly-favorited by a few readers.

There is very rarely any criticism or argument. The are not nested, they only appear in time-order. This keeps directed replies (and extended snark-fests) to a minimum.

The resulting 'civilized adultness' of the site is fairly unique on the Internet. Oh, and there's a small fee to join.