They need to work on their mobile web design. This [1] is not a pleasant experience in 2016.
Just look at how incompetently the site was redesigned: https://github.com/reddit/reddit-mobile/issues/247
45 seconds load time...
There's also the tiny buttons(obviously not mobile-first, even if it is a mobile-only redesign).
And of course, the poster child of "we are doing complex JS stuff, but still think that JS is for kids, so we didn't bother learning how to actually do it". I'm talking about the infamous "We built a single-page-app, but it doesn't always work right, and the back button is kind of broken, and it sometimes treats scrolling over a thing as clicking on that thing".