Fantastic post - thanks!
I would just add that this specific question has been a corollary to the question of whether Mr. Page suffers from some type nerve/tendon damage to his hands - all speculative mind you, I can't buy into one of the prevailing theories that it was just a case of him being junked out of his mind from 1975-1984(ish). There are loads of great guitar players who found comfort from the white nurse that remained or post recovery regained their playing chops. Perhaps in his case it was a cumulative effect of not being a particularly disciplined player (not a bad thing IMO), the drugs/drink and some sort of physical injury - a bit like having a guy who rarely runs, has a bad knee and is a chain smoker is then asked why he can't a run a mile in less than 7 minutes