A lot of the most popular content is "long-form" for no other reson than Youtube's 10-minute minimum length requirement for monetizing via ads. Video makers have responded to this arbitrary requirement in exactly how you would expect, by padding out the video length with dull filler material.

Think of the amount of writing that goes into a single 20-minute TV sitcom episode. The most popular ones have 24 episodes a year. Youtubers are expected to come up with 10-minute episodes 1x/week if not more frequently. The quality of the videos take a nosedive, the creators burn out, and subscriptions and views fall as a result.

TikTok's shorter videos can arguably be more entertaining as there's no arbitrary length requirement that incentivizes filler.