Yes. But they don't know it. They just know that their site is faster than their competitors. I've got a smallish piece of JS that gives the client a WYSIWYG editor, which speaks to Firebase. When Firebase gets an update, it triggers a rebuild. Best of both worlds.
That's very interesting. Is any of this code open-source?
The Firebase part?
I'm afraid not, but mostly because it's both simple, and fairly reliant on architecture.
Basically the process is:
Firebase authentication -> Content editable editor -> Firebase database update -> GitLab CI -> Pandoc & bash to update static site to latest Firebase -> Deploy to website