How can problems with shafts lead to premature cv boot failure?

I previously asked a question about why cv boots can fail and reasons given were cheap quality boots, improper installation and problems with shafts.

Regarding problems with shafts, what exactly might be wrong with them that they would cause a cv boot to fail prematurely?

I do remember that before I did these boot repairs, the torn boots had lead to knocking sounds(dried grease) coming from under the car for the most part of one year though I didn’t drive much. After the repair the knocking sounds had gone.

Thanks.