Two operational requirements:

1. Journalists shall be able to write new articles and publish them ASAP, possibly from remote locations.

2. Eyeball optimization: Different titles, cutting summaries where it piques interest most, some other A/B testing... So you need a data structure which can be modified non-destructively and autonomously.

Plus many more things, possibly. I love static webpages as much as the next small-web person, but we have small-web, because the web is not "small" anymore.