It's mostly because it's an old website :-)
The Paradox version began in 1999. At the time there were few suitable databases (especially one's with a good development language). (Plus I had some experience already with Paradox.)
Now many years later, I have a huge code base (25,000+ lines of code) that generates a website that is about 50,000 pages.
When data is changed (updated at least a few times a week), a flag is set in the data. The code then creates the webpages that are new or have changed. Then I just upload the new pages onto the web site.
(So the site is dynamically created, but statically served.)
Eventually I'll have to move to a different platform - but I dread the change since I'll have to re-create the code in whatever new platform there is.
The data exists in several dozen highly interrelated databases - due to the nature of the data. Which works out well for the website, allowing obvious cross-references to become links.