One of the original recipients of the "Substack Pro" advances -- a discontinued program where Substack would front a large sum of money to larger creators to incentivize them to use the platform -- explains why he moved his publication to Ghost. If you follow the debate about Substack's evolution from a newsletter platform to a multi-functional publishing tool, then most of his reasons for moving won't surprise you. Basically, he's suspicious that Substack is more focused on user lock-in than allowing creators to amass an audience they actually own.

I still don't really understand these arguments, seeing as how Substack hasn't actually removed any email signup capabilities. If I want to move off of Substack, I can still take my email list with me. Sure, Substack has also added in "follow" features that allow people to read my work without entering their email addresses, but that hasn't stopped me from maintaining accounts on LinkedIn, YouTube, or any other social network. So why is it a dealbreaker if Substack adds a "follow" button as well?

Obviously, this calculus would change if Substack suddenly made it much harder for people to sign up for my newsletter, but as of right now Substack doesn't make money unless people convert into paid subscribers, and you currently can't become a paid subscriber without handing over your email address to the creator. Therefore, Substack is still prioritizing email signups over follows.