I think my card is buried in my wallet somewhere.

For those of us who came from US Airways, the cards were sometimes needed to access partner lounges, particularly LH. I remember many threads in the old US forum about the LH lounge agents denying entry without the physical card (a printout sometimes worked, this was before phone apps). I remember going to the LH lounges in both MUC and FRA and I would just give them my card with my boarding pass.

I can't remember needing to show my AA card ever since the merger.