Mumsnet is weird about PCP's! These threads are always the same. In certain posters mind the only "correct" course of action is to save up and buy a cheap secondhand car outright. This car will last for 10 years with no major breakdowns and be cheap as chips (apparently!)
I don't think PCP's will cause a financial crisis no. They've been around for ages and the actual cost of a car is quite low in the grand scheme of things. You're essentially paying for the depreciation so the asset is still available to be recovered by the finance company in the event of non payment.
If you take out a loan to buy a car you still have to pay for it if you have a change in circumstances and pay interest so that doesn't go away.
Some cars do breakdown and are money pits. Some will run for a decade with only servicing costs. Unfortunately, you just don't know what you're going get before you buy it when going secondhand. There was a post not long ago by a poster who had spent £5k buying a secondhand Audi (having saved for years) which had done nothing but breakdown and she couldn't afford to fix it. The car wasn't worth what she paid for it and she was stuck. It does happen to people.
It's perfectly normal to pay more for something to have an easier life. I pay extra to have my shopping delivered because it's more convenient. I pay extra to have my car serviced by the local dealer because they will collect it and drop it off. I know I could get it done cheaper but I don't want to.
As with anything in life some people will get themselves on bother by biting off more than they can chew. Lots of people are merrily paying their payments and driving their cars without incident and will continue to do so.
If you don't like the idea of PCP then don't enter into one, no one will force you!