Substack has a different financial incentive structure that attracts writers away from alternatives such as Medium.com or hosted WordPress:

- monetization is easy to go from "free" to "paid newsletters". The pricing is set by the author and the revenue isn't shared with other writers

- for paid subscriptions, the writer has the subscribers' email addresses for a more direct relationship

In contrast, Medium does not reveal email addresses and does a revenue share of a flat $50 subscription price.

Looked at a certain way, Substack replaces MailChimp (an email audience relationship tool) more so than Medium.

The founder of Substack gave an interview and he said that Substack is a SaaS backoffice of Ben Thompson's "Stratechery" paid newsletter. Ben was one of the early pioneers of the paid email newsletters resurgence but since Substack didn't exist, he had to string together the payments and emails logistics himself. The later writers wanting to get paid for newsletters can just use Substack instead of reinventing Ben's tech stack.