Sometime around the night of the DNC primary in 2015 there was a dramatic shift in the content on Reddit. If you were a frequent visitor of the homepage and /all at the time, you will know exactly what I am referring to. The product has gone downhill ever since. Comment search is nice because it enables users to find interesting content directly in the good niche subreddits.
the_donald brought a lot of a younger users and white supremacists. I haven't seen a DNC-related reddit conspiracy before though. Certainly no noticeable shift that night.