There's a mod button called 'Sink'. It's a softer way to close a thread as it doesn't force the existing partipants to stop but does naturally reduce new participants joining as a result of the thread not bouncing up the list.
Having just read over this, seems it went quite a bit off-topic. So given the original subject matter I can see why a soft-close was actioned. Personally I like threads to live free and die free but I accept a forum can quickly get messy and confusing if people don't take that rule seriously.