There's an asterisk to that: they serve the underlying content through two different APIs so one can side-step the HTML wrapper around the bytes: the discovery

There's an asterisk to that: they serve the underlying content through two different APIs so one can side-step the HTML wrapper around the bytes: the discovery phase has a formal API (both REST and GraphQL) for finding repos, and then the in-repo content can be git-cloned and one can locally index every branch, commit, and blob, without issuing hundreds of thousands of http requests to GH. One would still need to hit GH for the issues, if that's in scope, but it'd be way less http requests unless your repo is named kubernetes or terraform.