CESA at birth! you do know what function the umbilical cord serves don't you.
This is SB, there will be someone with umbilical failure or someone who knows someone who had it.
The diver had a pony with him which he failed to deploy, that is no more the fault of the pony than a seatbelt that isn't fastened is responsible for someone being thrown through the windshield.
Seatbelt is a passive device once you buckle up it is in use, pointless to discuss or compare. According to the neutral data, people do fail to use the pony correctly or not able deploy when needed. That is that. You are making too many assumptions, I don't, I look at the data and probabilities. People prepare for events for years and yet still fail to perform at that critical moment. There is no guarantee that you will not fail one critical moment even you are prepared.
When a diver descends on his O2 deco bottle toxes and dies do you blame it on the deco bottle or on diver error
Again, weird, irrelevant example. The way I interpret this is diving with multi gases can be fatal. I do not blame the gear or the diver. There is no data on divers competence except he made this one mistake. You might get killed failing to turn on or check your valve, even you did it 1000 times right.
Two issues, one diver claiming any dive to 120 feet is a technical dive which most agencies would not agree with. The dive I did to 45m was a planned dive.
My TecRec deep diver material from (2001) defines rec scuba as:
No stop diving with air or enriched air to a maximum depth of 40 metres/130 feet, and during penetration dives, within the natural light zone and no more than a total linear distance of 40 metres/130 feet from the surface.
Tech Scuba:
Diving other than conventional commercial or research diving beyond recreational diving limits. Further defined as and includes:
diving beyond 40m/130 feet
required stage decompression
diving in an overhead environment beyond 40 linear metres/130 linear feet of the surface
...
I was doing decompression diving long before recreational tech diving training and equipment was widely available (at least to me) and often casually. Casual does not mean fully unplanned. If you are diving within similar parameters that you did already 100 times, 101st time, your plan becomes do it like the last time +- the parameters that are slightly different for that day.
I consider 50m dive with decompression a "sport" dive, I and many others I know undertook this type of dives pretty quickly after initial certification. You have to remember that other parts of the world people learn with P2 (aowd) gas planning and use Bühlmann or Hahn decompression tables. Depth limits might differ in each country but the knowledge is provided. So staged decompression was part of normal sport diving.
Anyway, lets get back to pony.