[kedean]

It doesn't sound like it's meant for private social media, it's an alternative to the ultra-public social media that's gotten popular in the last few years. It's about broadcasting yourself, not contacting a small subset of people (hence why you can only publish to the entire set of subscribers). If you need secrecy, then a system billing itself with the term 'newsletters' is probably not for you.

The real benefit, as the article points out, is that the empty room problem is solved. Everyone already has an email address, it's your online identity, and email addresses aren't tied to one provider like a facebook account or a twitter account. If gmail dies, TinyLetter still lives. If TinyLetter dies, there's nothing stopping someone from creating an alternative version that imports old newsletters to reconstruct everything.