I agree that The Economist has not been declining. I believe that what is really happening is that, at some point, a reader will eventually come across an article where they are particularly knowledgable about the subject matter. To their horror, they proceed to read an article that is “fraudulent by omission”. The cherry picked facts (which are correct) are chosen to fit a narrative. Every article read after this is mired by scepticism and therefor the perceived decline of the publication. This is what happened to me back in 2015 and try as I might, I just couldn’t get back into reading that magazine. I really miss those ignorant days of blissful intellectual smugness though.
It’s like watching a movie where you only ever see the good side of the hero. Viewers do not want you to change their mind half way through or cause them to be confused by the muddy reality of things.