You can “block” people by adding them to the IGNORE list under your account settings. It used to keep you from seeing certain people’s posts. Not sure about now. I’m too lazy to try it
EDIT: okay I wasn’t feeling lazy anymore and I tried it. Basically, you can still see the username of the person in the thread, but it doesn’t display if they’re online and it doesn’t display their post. It just says “You are ignoring this person” and gives you a link to SHOW POST if you want to read it. So...it sucks, basically 😂