I hate to break it to you, but if you think TikTok has "grass roots content creators" vs Facebook having influencers, I have a bridge, as well as a TikTok content house to sell you.
But they do seem to be optimizing more explicitly for "user enjoyment" than other platforms, perhaps realizing that this is what keeps and attracts users and their precipitation eyeball-minutes in the long term. Youtube also (not always) does a pretty good job at this, while Instagram can be rough.
Another possibility is that TikTok's short-form content feed allows for a greater volume of feed to fit into the same timeframe. Twitter was popular because it condensed blogging into microblogging; TikTok's success is pretty easy to delineate from that logic. Even if you don't have an algorithm promoting enjoyable/affirming content, you're just more likely to encounter that content when you watch more videos.
Whether that behavior is healthy or not... I'll leave that up to people more educated than I. My guess is that trading the user's attention span for short-term engagement isn't worth it, though.
I'm with you, and I'm of the opinion that the current TikTok craze has more to do with its brand than its algo. Facebook is old and lame to kids. Even Insta and Snap don't have as much brand cache as TikTok right now because TikTok is the newest major player with the most buzz. However, it's the nature of all hype cycles for high-flying, shiny new things to eventually fall back to Earth:
https://www.kapwing.com/resources/tiktok-houses-list/