My general thought is that it is a last-ditch attempt to attain some kind of compliance for a strictly IC powertrain. The wear in the starter and engine bearings must be horrible. (I wonder if they use any kind of pre-oiler to reduce wear? I never could find info on that.)
https://www.audi-technology-portal.de/en/drivetrain/engine-efficiency-technologies/start-stop-system_en
https://www.knowyourparts.com/technical-resources/drive-train/audi-startstop-system-tsb/