You're right -- I very much doubt that even a tiny percentage of reddit's users know that they're using Markdown (it's mentioned as an aside in the "formatting

You're right -- I very much doubt that even a tiny percentage of reddit's users know that they're using Markdown (it's mentioned as an aside in the "formatting help" section). Plus, of course, it's only a limited subset of Markdown allowed there. Nonetheless, a tiny percentage of reddit users who know how to use the formatting still likely represents a majority of the set of people who know about Markdown formatting.