You are right, this is literally the exact use case for a CDN; serving static content around the world with low latency. You only need one origin server, or two for redundancy.

Of course, my setup is overkill. It's mostly something to play with.

But, I also serve HTML pages "myself." CDN is only used for assets. I want to control the integrity of the content. CSS and JavaScript files served by the CDN are protected by an integrity hash (SRI). If I could, I would also include images in this, but this is not possible (and not something that looks planned).