The thing is that the usernames are not very prominent in this UI. They're even always grayed out. It's like it's optimized to not distract users with posts' owners unless they need them. I probably could recognize more if posts came accompanied by profile pictures or something that stands out that's somewhat unique to users. As it is, my brain doesn't have to register anything about the user to read their posts.

The 3 usernames I do remember, it's because one's name somehow stands out to me from their use of capitalization (most use just lowercase), and the others because their username appears in other people's posts (e.g. dang).