A few reasons why people (like me!) prefer building static sites to server-driven dynamic ones, even ones cached on a CDN:
These are basically the exact reasons I went from WordPress to Jekyll for my personal website and could never go back. So much stress in setting up and updating it is now gone. Plus it was relatively easy to work in tools I wanted like Tailwind and Turbolinks.
To add, decoupling the frontend and backend can also be useful for client work. Clients love CMSs like WordPress because it's easy for them to mess with things, but sometimes they mess with things that they shouldn't. By decoupling things, they have the ability to make changes to content, but not to the frontend unless they know what they're doing.
Here's a good read that goes into why people would use a static frontend on a WordPress backend:
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