This seems intuitive, and also provably false.

Joe Rogan is currently running the most famous and successful podcast in the world, and those conversations routinely go over three hours.

Dan Carlin is on a lower tier, but still highly successful, and his podcasts are far more polished and produced and integrate huge amounts of research, and the runtimes are even longer than Rogan's.

Maybe written content doesn't afford the detail you're looking for, which kind of makes sense, because you can listen to a podcast while commuting, exercising, showering or doing various chores, but you can't read doing almost any of them. But I'd argue almost anything done in an article can be done in a podcast or audiobook, so maybe the current failure of long-form journalism is not realizing that the medium has moved on.