Not wishing to get into a fight with you again - but you did.
You pointed out many of the problems with altimeters.
You do wish, and often do...and no, I did not.
Altimeters do have errors, just as every other instrument in the cockpit lies to the pilot, from the reliable magnetic compass to an attitude indicator. All have errors.
None the less, there is a very valid reason why GPS is not the method for setting altitude, as we have seen, and why the barometric altimeter continues to be the method of choice, and of law.
Made the case for using GPS? Hardly. More like a ringing condemnation for an attempt to do so.
Pilot error. Pure and simple. No condemnation on the use of the altimeter, and really quite irrelevant as a comparison with GPS...as GPS wasn't invented at the time.
One could point to the use of advanced GPS and FMS equipment that's enabled crews to put airplanes into hillsides due to a loss of situational awareness, too.
The altimeter in the case cited wasn't at fault, and didn't fail. The crew did.
One of the things we do today before anything else when given a climb or descent clearance is set the altitude alerter. This ties in with autoflight functions, but at it's basic level provides an audio annunciation when approaching within 1,000 and 300' of the target altitude, as well as giving an audio alert for altitude deviations.