IIRC the first version of reddit and the Python rewrite were each more or less built in a weekend. They were neither scalable to millions of users nor heavily o

IIRC the first version of reddit and the Python rewrite were each more or less built in a weekend. They were neither scalable to millions of users nor heavily optimized to keep users on the site as long as possible. The latter point is relevant to a variety of UX decisions across many products and services. Making it easy, efficient, and pleasant for the user to do what the user wants may not be the overriding concern in the design.