Most web pages need to be able to be updated. I think the two most popular options for that are a CMS or a static site generator. In general it is easier for "less technical" users to update the content in a CMS. Hence you get a database for rendering.
Alternate analysis: Personally it is not surprising to me at all that a marketing website would be run on Wordpress, Drupal, etc. And therefore it is quite clear that a database connection would be needed.
Even with wordpress you don't necessarily need the database connection. Either a colocated reverse proxy can cache the result, or you can configure cloudfront or some similar 3rd party service which will not hit the origin unless it has to. Or you can even use one of the wordpress plugins which caches the resources/pages as static files.
It requires extra half an hour of work, but... it's probably worth it.
Alternate analysis: Personally it is not surprising to me at all that a marketing website would be run on Wordpress, Drupal, etc. And therefore it is quite clear that a database connection would be needed.