It looks like my original information is outdated and that newer generation cars do use the secondary O2 to adjust fuel trims to compensate for changes in cat efficiency.
https://us.autologic.com/news/fuel-t...-faults-part-2
I guess this means any simulation, whether electronic or mechanical has to accurately produce expected stock readings or the fuel mixture may be changed to compensate. What still confuses me is that plenty of people have gone catless and not changed the tune or used any form of secondary O2 simulation and not experienced any problems even though the secondary O2 would be reading significantly differently than before.