[skywhopper]

Real systems at Github's scale take far more effort to add features to than your gut instinct first stab at imagining how it's done. There's caching to consider, instrumentation to build, privacy and security to consider, UI decisions to make, performance implications, documentation, tests to write, and deployment details to finalize. This could very well represent a week or two of work for a developer plus some ops work thrown in.

That's not all that much effort, but Github's staff has plenty more to do: maintenance on existing code, bugs to fix, research to do, troubleshooting, improving older code, updating code for new architectural improvements, writing internal features that don't show up in the public UI, and there's also the fact that every feature you turn on means an ongoing commitment to maintain that feature for the forseeable future.