I would argue that just because teenagers flock to one platform doesn't mean a competiing platform is dead. Teenagers don't have the relevance people seem to think they do.
They typically don't have any money to spend, so where they go on social media doesn't mean much from a commerce standpoint . Even the so-called influencers on TikTok will stop influencing its teenage users when the users mature a bit and realize that most of what they see on TikTok is shclock.
In addition, TikTok is a Chinese company. It could bite (byte?) the dust anytime. All Xi has to do is arrest its owners, and it's dead.
Your general complaints about YouTube seem pretty well-founded, but I think TikTok is a fly by night operation that will be history in five years, hopefully replaced by the next generation of kids who are looking for something a little more substantial.