It doesn't need to be algorithmic - like Lemmy and Mastodon and Pixelfed all let people follow, like, comment, up vote without algorithmically promoting content.

Try Pixelfed for a good Insta alternative. It's open source, supports self hosting, and federates with ActivityPub.

Someone else recommended Lemmy which like Mastodon would technically allow me to make text-based posts, but I think both fall very short of what a proper blogging platform would offer. I mean, I don't think Mastodon even supports bold text.

Good articles have formatting, they have embedded images, they have citations, etc. A good publication has featured articles, they have topics and dropdown menus, they let you filter by author, etc.

What made Medium so great was that even though it was an open blogging platform, it made your work look so nice it felt like you got your writing featured in a real online publication like say the Huffington Post. Substack allows writers to build huge audiences and collect monthly subscriptions and make a blog that looks very personalized and legit.

Mastodon and Lemmy are more for sharing and aggregating content than managing original content.