You can write on your own user profile in reddit, I'd say is the equivalent to Microblog
Let's say you are /u/BaldProphet on Reddit
You go to your profile, click on "Write new post" and this post will not appear in any subreddit, but only in your own profile. It will appear on the feed on people following you and people who enter in your profile can read and reply those posts
This feature is mostly used in NSFW profiles (people self-promoting their onlyfans)