I use stick-on convex mirrors on the driver's outside mirror. I also adjust that mirror depending on whether I'm doing city or highway driving. For highway driving, I set the mirror to see more behind me than beside me. Maybe partly because highway driving often involves the cargo area piled high with stuff. If you're going to see very far behind you, you are going to see the rear flank of your vehicle.
My formative driving years were in a truck, so I never became dependent on the inside mirror.
Which raises a point others mentioned. The article assumes the inside mirror is fully functional. With cars having 5 headrests, and high back ends, not to mention the proportions and loading of suv's, bicycle racks etc, the inside mirror is often severely compromised, and the positioning described in the article may itself be outdated.
The article also falls short in that it does not address added convex mirrors and the fact the passenger side mirror is universally convex these days. Is the writer unaware of these things?
Almost regardless of the circumstances, I check the right outside mirror when turning right to make sure there are no cyclists there.
Your point about the inside rearview mirror not always being usable is fair comment, and in that situation sure, you may need to adjust your mirrors a little further in (I guess this falls under the old rubric that "All generalizations are false.")
As for your comment regarding passenger-side mirrors being universally convex, and my apparent unawareness of this ... oh boy.
Sure, passenger side mirrors are slightly convex (slightly, because if you make them too convex the image becomes almost too small to be useful). But even the expanded field of view offered by a slightly convex mirror is made far less useful if the mirror is adjusted so that most of that view is the side of your own car.
All this was made quite clear in my original 15,000 word essay, but the editor said Internet attention spans simply aren't that long, and that the article was supposed to be a rant, not an essay.
He also didn't like my original title, which was "The advantage of adjusting your driver's side exterior mirror, and to a somewhat lesser extent your passenger's side exterior mirror, slightly further out in order to reduce blind spots." He said it wasn't catchy enough or something. Damn editors!