It might actually need calibration.

And if it does it would damage the reputation of Apple's products (iPad and Pencil) as they won't work accurately and will glitch, creating a subpar experience which Apple would obviously not want to be associated with their products.

Calibration is like wheel alignment. What is happening here is :

Changing tires for same brand and model car came from the dealer. Car no longer drives in a straight line, steering wheel feels wobbly at certain steering angles.

You saying its a wheel alignment issue.

Replacing TPMS sensors with ones from the old wheel set. Car magically starts driving straight and no more weird wobbles.

More like putting on the new wheels but forgetting to put enough pressure in them.

Turns out wheels came off another fully working car and worked perfectly fine before being removed.

The _only_ difference is TPMS sensors serial numbers.

The Apple Pencil is designed for extremely low latency and high accuracy to make it feel as close to writing on paper as possible. The API offered to developers presents predicted digitizer points and retroactively updates them in subsequent frames because even the latency introduced by a standard 60/120Hz draw loop introduces cognitive dissonance - your brain can tell something is off if you wait for the next frame update.

People are making a lot of bold claims with absolute certainty without so much as a test rig... how they can determine that such precision doesn't require any calibration or that using the old controller with a new screen is "accurate" is a very interesting question. I'm not sure drawing a few lines in one app is sufficient to draw such strong conclusions.