Is tonearm bias a compromise, maybe a myth?

the anti skate required is a function of the tone arm and cartridge combination. It cannot be correctly set by matching the tracking weight. A test record with oscilloscope is the best method to set tracking pressure and antiskate. the sine wave will show deformity until both are correctly adjusted. If you do not have an oscilloscope, listening to the test tones for uneven distortion can approximate the correct antiskating.

Incorrectly set antiskating will cause 1 side of the stylus to wear out sooner than necessarry.

Wow, setting anti-skate by scope? I'm sure it produces great results but did manufactorers really expect customers to calibrate at this level?

Amount of AS is necessarily a compromise, but with a pivot type arm there's going to be skating. Amount of skating depends on more than just VTF. It increases with stylus velocity and steeper offset angle. It is caused by offset angle - the plane of the cantilever is extended off to the side, rather than aimed at the pivot as in a linear type arm.
So set your AS for "normal" loudness of most of your listening fare, not highest velocity on a test record. Offset increases as the stylus nears the center of record. Too little AS could add to inner groove distortion. Amount of AS is a compromise, but not a myth. Channel imbalance is readily seen on a scope or with newer software available. Carts with long cantilevers - skating can be observed visually if viewed from directly in front of cart while playing. Either the cantilever is almost centered relative to the body, or it's off to one side or the other.

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This topic has been done more times than Madonna.

What Fleib and Audiofeil said. But I'd rather do this topic again than Madonna.