That's it: Self-destructing posts are like the *opposite* of pinned-posts.
You pin a post when it has something you want all future visitors to see it when they look up your page.
You make a self-destructing post if it's okay that some people see it now, while it's timely, but that you don't want to leave a big pile of on the profile that introduces you.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!