This is the point: the overwhelming majority of websites, especially blogs, articles, and general information such as store info, services, portfolio, opening times et al, could all be static instead of running a database query on every page load.

Caching on CMS like WordPress via plugins helps, but they still query a database on each page load. Ergo, the rise in popularity of static site generators even on top of WordPress. Not everything needs to read from a database for every page load.

tl;dr, not all websites need to "do" anything other than serve static information, but the way in which websites are commonly created and served is piss-poor. Just because the served content is static files doesn't mean that a CMS can't generate it if users want a graphical editor in their browser, and still want their theme of choice.