It is sometimes true that old posts come up in searches, and via links, but you don't get paid after the 6th day for votes so they tend to die out. Some estimate post life here in minutes even, not in days, because of the sheer amount of content pushing them rapidly down the feed. If it's not seen and resteemed a lot in the first few moments, your post is as good as dead Captain. So this is a way for a handful of viewers who either come to your blog and read back deep into it or random searches that turn it up, to add some value to it via continued monetization. I just read this post and know nothing much about the poster or the advertising idea, but I do know what I just said about posts is true.