It may be as old as politics, but that practice took a significant uptick when FOI requests started to make their way through politics.
Don’t get me wrong, I’m all for FOI practices, and openness, but the law of unintended consequences is in full swing here.
Future historians will have all sorts of diaries, memos, documents, and such that give an incredible amount of insight into the deliberative process, what people were really thinking, what they really thought of other politicians, what made them chose a certain policy option, for everything up to mid-1900’s. Everything after that, all you’re going to be able to find is the final documents, and things made with the knowledge that everything is FOI-able.