I'd say you summarized it fairly well. I did my NAUI ITC in '78. Within a few days, I received a letter from something called PADI. I'd barely heard of it. The letter was an offer... send us $25 and we'll send you a PADI Instructor card. I declined, and never really regretted it.
At the other end of the spectrum, my daughter spent a season in Utila, where she learned to dive. It seems like every other day, she completed another certification. It got ridiculous when she told be was going to be starting a DM course shortly. She had NEVER been diving outside of a course. I went down to visit, and she had reasonable knowledge, so my concern wasn't so much with the actual training, but the fact that she'd spent more money on instruction than I thought was possible.
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Well, everyone doesn't have 14 cards. I only (literally) have 13. A few of these (7 I think) were specialties, 5 of which I took to get the much maligned MSD card. The other 2 not really sure why. I really don't use most of the stuff I learned in those specialties, but it can't hurt-- no knowledge can hurt.
So why did I do this? Back then (2006-9 or so), I had the money to put out on stuff like that. Now, if the money wasn't available, I would not have in any way considered taking those courses. MAYBE gone just through Rescue Diver and DM.
If people are stupid enough to be "card collectors"--or spending a ton on unnecessary new equipment when the money is not really there, well...... PADI offers the courses and will gladly take their share of the fees (materials, card, whatever).