They're generally useful in promoting temporary content such as festivals. In places such as Instagram they're found their use in being used for casual posts that aren't of the quality of the users more cultivated actual posts. For example promoting a friend's page or casual holiday pictures. Particularly if the account has a brand such as hand made goods, it's a place for the owner to post personal content too.

I don't actually know what PixelFed is really but I currently only use web content where I don't really follow people as much as ideas and content, I couldn't name a single lemmy or Reddit user, I only follow hashtags on Masterdon and I don't really have much loyalty to who I watch on YouTube, so this content doesn't appeal to me because I don't often care about their stories. If PixelFed is a content site where you do follow personal content, then it's probably right for them.