We did have some configuration - it was stored in Varnish and Nginx. The time cost of shipping new redirects when content is moved or new routing configuration for new tools coming online is non-negligible, particularly as we're in the middle of moving 300+ government agencies onto the GOV.UK platform. Also having all those redirects, friendly URLs, and application mappings in static configuration makes self-service publishing tools very difficult to build.
This is all outlined in the blog post - perhaps not as clearly as I would have liked, though!
This is all outlined in the blog post - perhaps not as clearly as I would have liked, though!