I was banging my head against this earlier last week. It was such a jarring change to visit GitHub and not be able to navigate. It gives me pause to see how suddenly an easily-navigable site can become almost impenetrable with the removal of a single search bar. What are they thinking? The "Explore" menu is worse than useless, too.

It is an interesting case study in UX - the difference between a great experience and an awful one can come down to a single, well placed search box.

What is GitHub's rationale behind this jarringly awful, blatantly bad decision?