Yes, I saw that setting too but often I see a post and I want to come back to the post at a later stage to see if anything new was added to the conversation. On the commect app, I had the possibility to hide individual posts, which suited my needs better
What you can do there is turn on notifications for posts you want to follow. There's a little icon at the bottom of each post and comment, which will make you receive a notification if any further comments are made in reply to it.
Also, given that the feature to hide viewed posts already exists, it should be a viable option to let people manually mark posts to be hidden. You can request that with the piefed devs if you like