This is an idea I've been interested in since it came up last month (https://news.ycombinator.com/item?id=27582145), but I don't personally feel strongly enough yet to land on either side.

That being said, for all its faults, I would expect that reddit does indeed have more productive discourse than most other (non-HN) social media platforms, particularly Twitter with its enforcement of shallow/short-form comments. /r/the_donald is obviously an extreme example of an alt-right cesspool, but it's not obvious that it was less polite or constructive than the equivalent communities on other platforms.