I didn’t downvote but I object to this part, especially for beginner learners:
> The litmus test for someone who knows truly how to draw is to ask them to redraw whatever object they drew but from a different angle or perspective. Most people to learned by measuring and training their eye won't be able to do it.
How many of us, when we encounter a piece of artwork we appreciate, really care if the artist is able to redraw the object from another angle?
There are some limited circumstances where I can see this skill being relevant: for example, if you want to publish a series (a visually elaborate webcomic or such), or you want to be hired to work to spec doing e.g. animation or storyboarding. That aside, just being able to draw something others appreciate—even if that involves shortcuts and working around own limitations—sounds like an important stepping stone and a source of dopamine that can motivate further learning, which could eventually get you to mentally seeing things in three dimensions and being able to draw an object from any angle.
A parallel I can draw from personal experience is with music. We don’t make students learn notation and music theory first; we start with actually playing, practicing the motions, stretching fingers, learning to hit the right keys/buttons/strings, etc. If you get to being able to just play cool tunes, that’s good. If you don’t advance past that, some would consider that unfortunate and I won’t argue with that, but invalidating this stage outright sounds like unnecessary gatekeeping.