I was thinking mostly about "Even in novels, characters can have long conversations with only occasional references to their actions." In a novel scene, writers don't have to do that because they don't swap character perspectives each time a new character speaks.

Meanwhile in RP, where the perspective does switch every tag, just putting in the conversation part seems too short to a lot of players (especially in prose) and so they cram in lots of actions or thoughts because they feel like they have to make it longer or more interesting somehow.