Sure, but it's unlikely you actually have to place a CDN in front of your manual, it's mostly text with few images. People default to using CDNs way too quickly today.
Personally, software engineering for me is mostly about trying to avoid accidental complexity. People obsessing about "web scale" and "distributed architecture" before they even figured out if people actually want to use the platform/product/tool they've used tends to add a lot of complexity.
That's not really true if you care about reliability. You need 2 nodes in case one goes down/gets rebooted/etc, and then you need a way to direct traffic away from bad nodes (via DNS or a load balancer or etc).
You'll end up building half of a crappy CDN to try to make that work, and it's way more complicated than chucking CloudFlare in front of static assets.
I would be with you if this was something complicated to cache where you're server-side templating responses and can't just globally cache things, but for static HTML/CSS/JS/images it's basically 0 configuration.
People simply do not understand how expen$ive AWS is, and how little value it actually has for most people.
A lot of other people also pick it for very narrow use cases where it wouldn't have been that much more time to learn and do it themselves and end up paying a lot of money and also aren't happy
It's pretty nice for mid-size startups to completely ignore performance and capacity planning and be able to quickly churn out features while accumulating tech debt and hoping they make it long enough to pay the tech debt back
You can just drag and drop a folder and have a static site hosted in a few minutes.
