Right, but if the backend goes down, and you serve a stale cached version of the page that is missing the latest edit, it's fine and you have no downtime. That's what I mean by static.

The opposite of static would be an e-commerce site where you can't take transactions if the backend is down and you really don't want to oversell your inventory, so you need the inventory management system to be up for the site to "work".

Also, the average wikipedia page probably isn't edited very often.