Uh, are you asking why a site with that doesn't use cookies in a purely functional manner has a cookie banner?
In any case, it's the usual reason: they have google tracking, and it seems like they embed content from other sides the easy way. You too can learn the answer to the mystery of why there is a consent banner by clicking the "Privacy policy" button, this one actually explains it clearly, like it was supposed to be a model example or something.
Actually the unobtrusive cookie banner as implemented on that site is illegal under GDPR. Check out https://ico.org.uk/ for a correctly implemented popup with its dismal UX.
In any case, it's the usual reason: they have google tracking, and it seems like they embed content from other sides the easy way. You too can learn the answer to the mystery of why there is a consent banner by clicking the "Privacy policy" button, this one actually explains it clearly, like it was supposed to be a model example or something.