1) Online advertising is horrifically ineffective.
2) Online advertising is the primary method of remuneration for the lion's share of the internet.
3) Online advertising has, nonetheless, annihilated traditional advertising and thus, driven traditional advertisers online.
4) Traditional advertisers are unlike online advertisers in that they demand metrics to refine their advertising. As a result, the futility of online advertising grows increasingly obvious, driving down the prices of online advertising and driving down the remuneration for the lion's share of the internet.
5) Substack is first-past-the-post to say "give some away for free, sell some more, we take a cut"
6) Substack becomes the de-facto home for quality content.
Ryan Holiday, back when he had a point to make, made the point that "journalism" as we know it came about when the New York Times started selling subscriptions to their paper, thereby reducing the pressure to rely on sensationalism. Within a couple years the yellow sheets were entirely done and America had a Fourth Estate. The British never really figured out "subscriptions" which is why their journalism remains tit-driven.