Is it? You've taken two facts (1. Interface redesign and 2. 50% growth last year) and assigned causation to the first. In my persepctive, reddit has been digging into the cultural psyche for a long time and has been growing steadily. The news uses it to replace local journalism now. Anecdotally, a lot of people I know are now talking about things they saw on reddit (I've been a user for ~10 years). I think the interface design is not relevant to growth. If anything, it probably decreases it, although I think the type of users they are attracting now don't care as much as people who post on HN do.

The simplest argument is that the default is usually... defaulted to. And the default is the redesign -- you have to actively go out of your way to revert to the old design; so the simplest takeaway is that the general public greatly prefers doing nothing, than reverting the redesign.

Doing nothing may be for the reason that they prefer the redesign, but also numerous other reasons apply (including that they don't dislike it enough, or some key new feature, etc).

Did you know that tax revenue almost always increases after a tax cut? Did you also know that tax revenue almost always increases after a tax increase? Aren’t statistics cool?

October was also an election month, so I would assume that more people were checking in to read the screaming matches.