I think you missed the point. It's not the developer's convenience. It's the readers.

Each blog post is going to get written once, but read (hopefully) thousands of times. Why are we optimising the writing experience and not the reading experience?

> It's not the developer's convenience. It's the readers.

The marketing folks and copywriters are being paid to post, and they have a manager and boss to report to - which can fire them.

I guess it's very much about convenience and ease of use to people writing the posts

Readers don't care at all whether they're served WP or a static site.

The GP doesn't have a point to miss.

Sure they do. They don't know about WP or static site, but they do know about "how long does the page take to load" and does the page work properly. It's certainly possible to build a WP set up that is super fast (and basically a SSG), but the vast, vast majority of them will not be done like that. They'll be loaded with a bunch of marketing plugins that kill performance and routinely throw errors that manifest to the user as some broken button or form that won't submit properly.

It's possible, but much harder, to build a static site that performs as poorly.