>Forcing bloggers to manually opt out of email delivery every time they publish a new post is not only inconvenient, but also prone to human error.

Huh? This is not even wrong. First of all, Substack is primarily (and has been touted as such) a newsletter (email based) platform, not a web blogging platform. The web version of a newsletter is supposed to be secondary.

Second, it makes sense to give all users as a default, and "restricted" reach to paid subscribers as an option.

Third, if I follow someone, it's precisely because as a reader I want to get notifications when they post something. Couldn't be more explicit.

Forth, a dark pattern (and still arguable at that) would have been prioritizing paid-only posts, since those are which give Substack money. So the total opposite.