You must have blocked /r/t_d. I would trust that there would be little argument that, by number of subs, and subscriber count, Reddit leans pretty-heavily left. However, by front page posts, the site APPEARED to lean heavily right in the run-up to the last presidential election. Week after week, I was blown away that the admins didn't nerf the algorithm to "fix" it.

They did eventually nerf the algorithm. /r/t_d was abusing stickied mod posts to get on the front page and that got fixed. I think it was also partly because most of the pro-trump users and posts were concentrated in one subreddit causing inflated upvote counts.

/r/t_d also took advantage of the void left after the DNC primaries ended since the site was very anti-Hillary at the time.

Reddit is not a single entity, it is a clustered social network. The small part of it that supported Trump managed to create and empower a meme machine that is still going strong.

Subreddits are like thinktanks. They are the perfect breeding ground for internet content. You can gauge popularity, you can quickly refine the content based on the comments received, and if you're lucky you can even kickstart and guide whole movements.