You are not wrong but it hardly matters for most blogs/product web sites. For example, I generate my blog from markdown with a custom generator written in not-

You are not wrong but it hardly matters for most blogs/product web sites. For example, I generate my blog from markdown with a custom generator written in not-very-optomised Python. There are about 400 pages currently and it only takes about 2 seconds on a 6 year old MacBook to completely build the entire site. Even if I write another 1000 blog posts each year, generating the site will still take less than a minute for the foreseeable future. Paying the cost of building the pages up front like this is still much better than having my users pay it by waiting 10s of seconds from the page to slowly be dredged out of a database. There are sites that do have tens of thousands of pages, and perhaps a content management system is appropriate for them. Horses for courses and all that.