There is frequently a reverse proxy in front of all web services. It’s got nothing to do with the quality of the implementation behind the curtains. And “the actual load” is by definition managed by the endpoint not the router.

I mean it would be trivial to implement that reverse proxy in Go. And I do mean trivial; Go also includes a reverse proxy utility, so you can implement something basic in about 5 LOC.

At this point it’s hard to believe you’re being genuine.

So trivial that it isn't usually the case.

A weekend project and going at scale isn't the same thing.

Kubernetes API server is not dependent on Apache, NGINX, HA Proxy, IIS, ... taking care of the actual load, since it's not getting any significant amount of traffic. In general API servers have much bigger scaling problems with actually executing the API calls rather than handling requests at scale. Having an NGINX or something similar to serve some static content and also reverse proxy to a Go server is sometimes nice if you're also serving a large UI app, but in that case NGINX is very much doing trivial work, and Go net/http is handling the real work.