> For something as simple as a dismiss button for a particular promotion, it's reasonable to store the bit on device. This will work for mobile and desktop apps, which I assume are the vast majority of Spotify usage.

No it isn't. When you "dismiss", the service needs to have a point of view (or UX to clarify) whether you want to dismiss it permanently or temporarily (I'm not in the mood for it right now).

You also need to deal with the cases where someone accidentally hits the button.

You also need to think about people who use multiple devices.

Should the algo's now update to say you don't like podcasts? You don't like talk shows? You don't like podcasts with themes that Rogan covers - what themes would that be?

etc.