I'm not able to do a mini-scientific study on this, but I'll assume some of those people who post their BPs, QR codes, and other personal info might be the same bunch who post endless amounts of selfies, some perhaps with minimal clothing etc
....


As for the AC booking reference number, if it is not included in the email confirmation and say instead, you are required to write it down as it's only available during booking, you'll have the AC phone lines flooded with people who forgot to write it down or lost the paper or deleted the note from their devices.