I don't think this is entirely true. Have you seen these "Internet Story told by TTS Voice-over a Minecraft parkour Video" ( which are what my niblings watching ) ? I noticed a lot of the story is dragged on for over minutes. These are the stories that I read in text in about 5 second.

Short form videos are often hyper focus and to the point, but there are a lot of vertical video contents that are just ( to use the GenZ term ) brain rot like these as well.