A minimal HTTP server that recognizes GET requests, finds the url, throws away everything else, runs the relevant code and returns an HTML document of the results is actually really easy to write. And easy to integrate into an existing event loop.
But even a minimal HTTP server, even one that ignores things like HEAD requests, is still going to be more complex than, say, receiving the URL raw, or even a URL wrapped in a simple structure like a netstring.
Actually implementing a full, correct HTTP server would be one or two orders of magnitude more complex that implementing a more modern protocol from scratch.