Honest question:
* Do you understand OS syscalls in detail?
* Do you understand how your BIOS initializes your hardware?
* Do you understand how modern filesystems work?
* Do you understand the finer details of HTTP or TCP?
Because... I don't. But I know enough about them that I'm quite convinced each of them is a lot more difficult to understand than ACME. And all of them and a lot more stuff are required if you want to run a web server.