I'm with you here Dave - but I'm amazed how often I have to discuss this with guitarists in the shop. They ask about how I can age alnico to make it 'sound' like a particular guitar hero on a particular song.... I usually just advice them to drop acid
Do they not realise that the guitar heroes of the '70s were using relatively new gear back then? How quickly does alnico degauss anyway? Beyond that, Tony Iommi was using radgy-spec John Birch pickups, Jimmy Page used more T-tops than PAFs during a given gig, ask anybody how to get their tones and you will get a million unhelpful answers.
I've seen people talk about the quintessential Marshall tone Marc Bolan used on 20th Century Boy... talking about a Les Paul plugged into a solid state HH IC100 amplifier with the 'sustain' switched on. The tone is quite fizzy, brittle sounding, and nothing like a Marshall.
Jerry Garcia claimed that his Dimarzio Super Distortions lost their edge after a few years as the magnets had lost their potency. Today we know this as tinnitus.