the development of Octopus seconds and actual BCDs made diving safer... and more expensive.
I think that kind of thing goes in cycles.
I'm just guessing that in the very early days, scuba tanks (in whatever form they existed back then) had a simple valve. Then, somebody decided having a reserve would be safer, so they invented the J valve. I'm sure that was more expensive than its predecessor. But, eventually, somebody invented a reliable SPG and the J valve was replaced with a more modern and, presumably, cheaper valve. Meanwhile, overall safety was still better than before. And overall cost was also cheaper, because you only needed one SPG, no matter how many tanks you had.
I think current CCR tech is somewhere around the J valve equivalent.
My imaginary device above was somewhat dependent on being an SCR. But, imagine if:
- O2 sensors were solid state and stone reliable
- scrubber cartridges, including the manufacturing process, were stone reliable
- CO2 sensors were solid state, and stone reliable, even in a wet and salty environment
Then, somebody put all that together in an electronics package that was as reliable as a Shearwater Perdix.
All of that seems not here yet, but within reach of the next few years.
For people who are only doing recreational dives, a CCR built on that might be comparable in simplicity to OC. Comparable - not necessarily the same. It might be comparable in reliability to OC. And it might be in the ballpark of the same cost as a full OC kit. And, for recreational divers, maybe even deemed not to require carrying a Bail Out. We're talking about NDL diving. Maybe this imaginary CCR includes an OC 2nd stage that is plumbed into the dil bottle and that is the only BO required. Thus, this 2nd stage can be donated to another diver or used by the bearer. Or maybe the CCR has a BOV for the user AND an OC 2nd stage for donation.
I don't know. It just seems like a lot of the discussion of "requirements" of CCR diving reflect assumptions that are based on the current state of the tech and are not necessarily inherent to the concept of diving a CCR.