Spend time in any book discussion group, and sooner or later the question of editing quality will be raised. The problem may be blamed on publishers, self-publishing authors or editors themselves, but everyone will have a story of a book or article in which the editing was sloppy or non-existent.
There is some truth to claims that editing is in decline. When publishers cut costs they may be unwilling to pay for the time required for careful and comprehensive editing. Self-publishing authors may not recognise the need for professional editing, but instead rely on automated tools or feedback from friends. Anyone can call themselves an editor, and not all ‘editors’ are equally skilled.
But not all ‘errors’ complained of are genuine, and not all of them of are the responsibility of an editor.