Ah, but the side slip confuses this. In order to change your ground
track by 20 degrees, you need to change your direction through the
airmass by 20 degerees. No argument there I'll guess. But your question
is, why do we care? Because a turn to final that includes a side slip
at the end gives a false impression of which way the aircraft is really
going. In fact, there's no reason to align track and heading until
touchdown. We've already discussed why you might choose not to.

Clearly many pilots get this. But many more do not. Though I suspect
they are becoming less certain about their own notions of how this
stuff works.

If the deconstructions are too simplistic (or obvious), I'd argue that
it's needed. I quoted the Soaring Flight Manual earlier to demonstrate
that even our textbooks promote some questionable notions of flight.
(I'll offer some more examples later this week.) Remember my question:
are crabs and side slips additive? Why would you NEED both in a strong
crosswind? If you think they ARE additive, I'd like to understand how
and why.

As for the art of flight (your last few sentences), I'd counter that
any maneuver that we cannot adequately (and simply) deconstruct,
shouldn't be in our repertoire. Why? Because when things go wrong, as
they sometimes do, you may not have the "rote" skills to quickly and
effectively correct them. Remember, we're doing these maneuvers
infrequently, near the ground, in turbulence. Not a forgiving
environment.

If I'm digging deep, it's so I can backfill with a better grade of
soil. I'd like to condense this down to several paragraphs, but getting
it short takes time and effort and a lot of words. If, on the other
hand, you have a concise, accurate description, please share it.