The putter face rotates on its arc
The face still rotates on its arc during the stroke - opening relative to the target going back and closing through, to some degree. The only way the face could point at the target the entire stroke is if the putter were 100% vertical.
Channel: MrShortGame Golf
Watch official source at 10:28Why this context matters
Discussing what a zero-torque putter does and doesn't do in the stroke.