One thing Substack and TikTok seem to have in common is that both seem to have been built with people who are monetizing their online presence (i.e., influencers) in mind, while on YouTube and Fashbook, influencer content is something that evolved in spite of whatever portfolio of participants the creators of those platforms were trying to assemble. That being said, TikTok -> Substack sounds like a "pivot away from video." I do prefer the written word over the moving image, but something about Substack repulses me, probably the sheer frankness of the FYPM aspect, and of course there's their reputation as some kind of Nazi bar.

At the moment I have only one substack "newsletter" in my feeds. It seems to be one of those "above the fold" type feeds, but I can't entirely tell whether the writer just likes abrupt endings to posts.