There is no ratio behind the equipment choices, the guy just googled 'best scuba gear' looked on some boards and decided this is what he needed. Let's be real here. Everyone has done this to some extent as a starting divers.
I actually like the gear choices except the air2 inflator and the 300 dollar bread knife. But maybe he's just rich and wants to spend money, that's all fine with me.
What I don't understand is you complaining about dive shops stock management. It's a completely normal storefront business model. You don't put an order with the manufacturer untill it's worth it, else the logistic side of things will end op costing you your margins.
And the one brand policy is present in almost all aspects of business. You don't go to a Toyota Forklift dealer to complain about the fact he's not willing to sell you a Clark forklift or spare parts? It just doesn't work that way in any business, unless you are in the logistics business, where you just have one massive warehouse, but that's not feasible for any small shop.
And yes it's dying out, because people have gotten used to easy quick easy access to everything.
Is this a bad or a good thing, I don't know, but it's a weird thing to attack the business model of a dive store, which is basically the same business model of any small retailer. These big stores like amazon, zalando, asos etc. they do provide everything instantly, but it comes at a cost of exploiting employees.
Zalando (a big shoe online retailer) used to pay their german warehouse workers 5 dollars an hour for work that's basically slaving. If they didn't reach their targets they would get a warning, second warning, third warning out. The targets were basically unreachable unless you slave away like crazy.
They would pay Bulgarian families as little as to 3 ,5 dollars an hour. This was in 2013!!! Untill Germany reformed it's laws considering the minimum wage this was the reality for these 'flexi-workers'.
It's easy to attack small business models if you ignore all the ethical and economical issues these big companies cause.
The big online retailers have the better 'business' models, but it really comes at the cost of the employees.