Both groups made mistakes. When I was with UTD, we were told not to use the average depth feature of the bottom timer, because it included the ascent time. We were taught to check our bottom timers ever so many minutes and keep a running average in our heads. There is no question that they did realize that they had screwed up the ascent rate to the first stop, just as the second group did. The second group is also at fault because they were of the "the slower the ascent the better" school of ascending, which many people have said is the most common error in technical diving--they don't get off the bottom with the urgency they should.
But you missed the point. Both groups made mistakes. Both groups were unaware of the fact that they made the mistakes. The difference is that one group acted according to those mistaken beliefs, and the other group acted according to their computer's correction of their mistaken beliefs.
You can pick two convenient examples that support your claim. In the first group, they were following ratio deco, screwed up (by not following it correctly) and ended up getting bent. In the second group, they screwed up by ascending too slowly, followed their computer and didn't end up getting bent. Therefore, your claim is you shouldn't use RD because if you make a mistake you can get bent, and if you don't follow RD and make a mistake you can't. This is simply not true.
There are several cases where people follow 30/85, 50/80, some other GF, VPM-B +2, or whatever model you want to pick, and winded up getting bent. I can use the same logic you did, pick out two samples, and say the people who got bet using GFs, if they were using RD, they might have adjusted their profile based on the conditions and would not have gotten bent. The logic works both ways. If people screw up, all bets are off whether they are following RD, trying to follow RD, trying to follow a computer, etc. They are rolling the dice, they could wind up ok or end up with a bad hit. To be fair, I also know people who followed RD 2.0 perfectly and winded up with a bend, while several other people doing the same dive were fine. The same is true for any model you want to follow, sometimes it's undeserved, explainable by other external conditions (PFO, etc) and sometimes not.
I completed several hundred dives, including shallow training dives, in my UTD years. I was certified at Tech II. I took my Ratio Deco class from Andrew Georgitsis. That was a long time ago. I am honestly trying to understand what the current thinking is here, and this is your chance to show everyone what that is.
Below you will find two dive profiles from Multi-deco ZHL-16 C with GFs of 50/80, which is what I am currently using. The first is for a simple freshwater dive using 21/35 at sea level, and the second is the exact same dive at 6,000 feet. (I did it with 2 deco gases; I can change it to 1 deco gas if you prefer.) When I was with UTD, we would have done them both the same, but you say things are different now, and UTD will change practices at altitude.
Could you please post what those two dives would look like in current UTD practice? It doesn't have to be you who answer--any of the other UTD instructors reading this thread can fill in the information.
To be clear, again UTD doesn't teach altitude diving as part of ratio deco. I'll play along though, by depth adjusting for 6000 ft elevation and still using RD.
I'm not trained for two deco bottles, and I'm not trained to go to 180' for 30 min. I've completed UTD's tech 1 program (the new tech 1 is the old tech 2), which is max of 160'. Therefore, I'll depth adjust your sea-level dive to a depth of 130' instead of 180', because 130' at 6000ft of elevation is roughly equivalent to 160' at sea level. I'd also have to change the bottom time to 25 min because my training only provides for 30 min of deco, and at 160' I would get 25 min of bottom time and 30 min of deco at sea level.
Dive to 130', 25 min BT, 21/35 for back gas and 50% O2 for deco gas at 0ft of elevation
Note: I'd probably switch to 25/25 and a 100% bottle for this dive, but you kept the parameters the same between the two so I'll do the same. The deco gas is not as ideal as a 100% bottle.
Descend to 130ft at 60 FPM, level off at 130' for 23 min (25 min BT)
Ascend to 80' at 30 FPM
80': Stop for 1 min
70': gas switch to 50%, stop for 2 min
60': stop for 2 min
50': stop for 2 min
40': stop for 2 min
30': stop for 2 min
20': stop for 2 min
10': stop for 5 min
For completeness:
Dive to 130', 25 min BT, 21/35 for back gas and 100% O2 for deco gas at 0ft of elevation
Descend to 130ft at 60 FPM, level off at 130' for 23 min (25 min BT)
Ascend to 80' at 30 FPM
80': stop for 1 min
70': stop for 1 min
60': stop for 2 min
50': stop for 2 min
40': stop for 2 min
30': stop for 2 min
20': gas switch to 100%, stop for 10 min
10': slowly ascend 3-5 min to the surface
Dive to 130', 30 min BT, 21/35 for back gas and 50% O2 for deco gas at 6000ft of elevation
Descend to 130ft at 60 FPM, level off at 130' for 23 min (25 min BT)
Ascend to 80' at 30 FPM
80': Stop for 1 min
70': gas switch to 50%, stop for 3 min
60': stop for 3 min
50': stop for 2 min
40': stop for 2 min
30': stop for 5 min
20': stop for 10 min
10': stop for 5 min
Are these acceptable?