I would certainly never support or defend diving without proper training. I do think the question is interesting. Having been away from diving since the mid 90's, it seems odd that there are soo many certifications out there, as well as inconsistent stages and paths for advanced training. For example, Nitrox was just getting somewhat popular in the early 90's when I was active. I signed up and paid for the class, but due to travel schedule and life, I never got my c-card. I had access to the gas, and was very well versed in the training material. Shoot, one of my dive buddies was an instructor. Getting back into the sport now and am trying to re-gain proficiency and update all my knowledge base.
So.. I am a good example of somebody that does not really "need" a C-card for this particular dive profile (Nitrox). I have been trained, and am proficient. I have access to the fills, and know that safety is not an issue. I could go on diving at my current level without any issue. Would my life insurance refuse to pay out if i died while diving 31%?? Maybe.
Anyway, I am signing up for a Nitrox class! Not because I really need it, but because at some point I will need to card as a pre-req for further training. Plus it will help me get to know an instructor, before committing to a more advanced class.
I do think the dive industry can be in danger of cultivating a bit of an anti-certification mentality. Whe have all heard the P-A-D-I acronym right? I went to dive Dutch Springs with a co-worker back in ~'03. We had never dove together before, and he asked me where I had been certified for 'doubles'?. I said: huh?? I had never heard of such a thing. I learned to use them when strapped them on getting ready for cavern/Intro training. Seems like somebody was filling his head that you needed training for damn near everything imaginable.
Once again, I am not against good training. But it seems a bit much sometimes.