I really don't care how people spend their money. I am a finance manager at an auto dealership and I have seen people with excellent income so strapped in debt that the most minor deviation will cause them to spiral behind. I've seen people come in with excellent incomes and can't get a $12k loan for a Nissan Versa because they've only got one credit card that sits in a drawer they never use while everything they purchase is paid for in cash, on the opposite side I've seen people who have low income and high debt, but have never missed a payment in 10 years. In my experience, the guy that pays cash for the Mercedes that says you shouldn't finance the Mercedes typically likes to feel special that he can pay cash for a Mercedes.
I think the line of thinking that people shouldn't finance what they can't pay cash for could be on the same line as thinking people shouldn't get something like a Macy's card. Some people you talk to would go even further and expand this philosophy to credit cards, education loans, auto loans, and even home loans. Like religion or sexuality, one person's financial philosophies aren't always correct nor are they always wrong.
Would I personally go finance $1k worth of corals from WWC? Absolutely not. I might use one of the 0% credit cards I cycle through if I really want something and wanted to spread out the cost, but it's none of my business if other people use their financing option though. I will say like anything, this hobby can be addicting. Unfortunately, financing options for addicting activities can be dangerous. Regulations may step in at some point to limit interest, but easy online finance options have been spreading for the last few years, and their success will likely cause more to follow.