For sure. I had a huge following on my wordpress blog 15 years ago and email was how everyone got notified of new content. I'm sure there's a way to at least do sms now if people want that level of notification.
replyMost writers just want to write and don't want to start maintaining servers and databases to handle the collection and storing of emails. This is why they outsource that functionality to a service like Substack.
replyIt would be nice if services like Substack supported exportability, so when a writer eventually becomes successful enough to migrate away, or the platform itself is no longer a good fit, then there aren't any losses.
replyConvenience is good, but I don't want writers & readers to have to make a faustian pact every day.