The difference between propaganda, advertising, spam, and actual news is a subjective value judgement — and even the objective distinction between factual and false information can only be evaluated subjectively.

I don’t think a protocol per se can disincentivize propaganda — and I don’t think it’s possible to design a protocol around that goal.

However, any protocol that maximizes subjective value in general can be used to reduce propaganda— if “propaganda” is something people don’t value and they can identify.

I don’t think Nostr is such a system right now — at least not more than other platforms — but maybe it will become one.