Without an easy way to dig through old posts, I needn’t worry about keeping their content updated. Old posts naturally fade away and decompose.
There’s also a certain psychological trick involved, call it the pot of gold at the end of the rainbow. There’s the implied promise of posts worth reading, if only you knew the right search terms to find them. A wonderful conceit.
I'm not sure I agree, but there's something very poetic about this point of view.