Any repeated activity that causes shortening of the hip flexors can cause APT. This can be sitting for extended periods of time or any other exercise or activity that results in prolong periods of hip flexion or over activation of hip flexors without proper activation of hip extensors.
This is just a VERY vague and minimal summary of what potentially can cause the APT, as there are many other factors as well - tight QL, hip rotation ROM deficits, thoracic spine ROM deficits, etc.
To answer your questions: The powerlifters you mentioned probably have the "duck feet" more due to the typical powerlifter squat position - wide stand, externally rotated hips/femurs, toe pointed out. I don't see weightlifting "causing APT" - it is more due to not maintaining proper mobility, soft tissue quality, muscle balance, etc. So for a more correct statement, it would be something like "improperly balanced and structure weightlifting, along with poor daily habits, have the potential to cause APT".