For a text link site that lets you vote submissions up and down? Yes that's a lot. I'm sure a lot of the decisions at reddit corp were along the lines of, "well, we can't go back and change that now, so let's do whatever we need to fix it and move forward" AKA lots of RAM and caching all over the place.
If a company is grossing $20MM/year and stands to improve that by more than 0.75% by having a faster site, then yes, it makes sense to spend 0.75% of your revenue to do so.
If you think that's all reddit is (text link, with up and down), you have to go use it a little bit. Subreddits, comments, self-hosted images, etc disagree.
