It's a bit puzzling, why would you add an annoying banner for 'fashion' purposes? It's more work and if you don't believe it's useful (in this case to shield yourself from potential legal trouble) why would you do it?
The key part is that many people do believe it's useful when it's not.
It's management/legal saying "Oh no, we use cookies! We need a cookie banner!", even though the only cookie used is to track state or some such thing which doesn't fall under GDPR.
Exactly. You "have to have one" even if it is nonsensical or meaningless (a number of these banners are on sites where the ONLY cookie ever recorded is one saying you've seen the banner!).
