Counterpoints:

- TikTok remains a complete rip-off of Vine which it appears was too far ahead of its time.

- YouTube is watched as much on TV's as phones. This has led to some phenomenal creators using it as a platform for very artistic and entertaining stuff (eg Devinsupertramp, Dude Perfect)

- YouTube is the greatest educational resource in the modern world. A Teacher and need a quick video to back up a point? Somebody made one. Want a tutorial on how to do anything? Ditto.

- Videogaming is by and large the most successful entertainment medium on the planet and gaming streamers on YouTube are king. The likes of Preston, DanTDM, Markiplier, Ali-A (illustrated), Lachlan etc are all king. Nobody makes TikTik gaming content, likely due to the portrait viewpoint.

- You mention that the biggest YouTube channels are all 'celebrities' when the biggest YouTube channels all became celebrities. Ask the average person under 30 and they can probably name at least one successful YouTuber but there are no similar names from TikTok.