A feed reader that offers control over deletion of old posts is good, I agree. A combination of age of post and number of posts per poster would be great. Like "delete all except the previous five posts per feed". Wouldn't work in MB, of course ...
Because it is an inescapable law of journalism that a simple yes/no question in a headline almost always requires a "No". And in this particular case, I do not believe blogging waned in 2018. QED.
As usual, the answer to a simple question in a headline is "No!"