I can list some.... from the PADI course, Ditch and Don, Buddy Breathing, Tables.
In the recent raging debate on this topic, altitude diving and tide charts were the two most often cited items dropped from OW that one fervid participant hammered on repeatedly. Both are mentioned in OW instruction, but only to the point of saying a diver may need to know about them. The person arguing abou the diminishing of standards said that all divers should know the details about both.
Interesting, all of those were in my PADI course a year and half (2 yrs???) ago. We didn't practice the buddy breathing a lot, but we did it, we definitely did a ditch and don and we even did 1 altitude calculation though I must admit we didn't do any tide charts that I recall. We did tables and eRDP for my class though, again, not much with the tables. I don't see a huge difference as long as you understand how the tables work...
Maybe that's what I'm missing, the fact that things have been removed but may be still taught by some instructors.
My chief pet peeve of skills that have been deleted for safety sake, is livesaving training for divemasters. Not diver to diver, but swimmer to swimmer. The first time that an instructor gets to evaluate a student is during the swim test, and if they fail the swim test or have heart attack? I can't recall lifeguard training every being a pre-req which would have actually made more sense.
I was under the impression Rescue was a requirement for DM. Rescue requires Emergency First Responder training, so I'm not sure what agency you're saying doesn't require lifesaving training for divemasters. Am I incorrect in this belief?