Attention span is more and more of a problem nowadays, and it becomes obvious on Hive as well. But as you remarked, there are people who know and can keep their audience entertained for a longer post or video. Not many can these days. The style matters, the expertise matters, the willingness to say the right things or on the contrary, to avoid controversial topics, everything matters. And usually the most successful know their audience well or they cater to a certain type of people and interests until the audience becomes what they cater to.