Looks like either they changed the way the dates are stamped or it has to do with when the screenshot were taken. It doesn't look photoshopped to hide the year and the in quoted responses clearly show the flow of the conversation.
I agree, I just wonder the reasoning. Is it possible someone over there learns? And the missing posts could be boring, or omission of good stuff. I have skimmed some that was boring, but at least all the info was out there. Maybe I'm too pessimistic.