My interpretation is that in a powerlifting bench setup, the scapulas are retracted, depressed and actively pinned to the bench via thoracic extension (and lat tension obviously), so with the same bar path, the strain is shifted almost entirely onto the pecs compared to a traditional barbell bench, where the shoulder blades slide along the ribcage as the weight moves.
This setup also places the pec origin lower and more posterior (more stretch)
Another crucial detail: during a bench, powerlifters externally rotate their humeruses, which rolls the pecs outward (retarded term, I know) and increases stretch.

Look at the elbows

With all of this in mind, it’s not surprising that pec tears can occur during a powerlifting style bench press.

Thanks for the explanation. Now that I think about it, I can't think of a single bench presser in the sub-200 lbs category who has torn a pectoral muscle, and it's not uncommon for them to bench press 500 lbs raw.