If you don't actually want an answer but just want to argue the answers the thread will be closed.
It's very simple, the better the power supply the more stable the system will be and the less chance the power supply will fail and/or damage other components. There is no arguing that fact. If you are happy with a higher chance of failure, then get whatever you want, no-one is forcing anyone to buy a high end PSU, it's just recommended if someone is paying a lot for other components. Would anyone with a brain tell someone to buy a $100-200 PSU for a cheap system, no, but if someone is spending $800 on a video card and $400 on a CPU then they should get a comparable quality power supply.
Just like anything in life, having a lower quality thing does not automatically mean it will fail or damage something, but there is a greater chance of that happening vs a better quality thing. This is the argument that smokers and people that drive drunk use, well I did it for years and nothing happened, so it's OK to keep doing it. And people that want to get a low quality power supply say "my computer starts and runs fine with what I have" using the same flawed logic. Just because it is running OK now, or was running OK for a year, does not mean it will keep running well in the future and has a greater chance of failing or damaging something in that future.
To keep it simple again, let's say whatever thing has a 20%, 10% 5% 1% chance to fail at some point. That is what you are picking when you look at different quality power supplies. You may say to yourself, I need to pay 200 for 1% but only 80 for 5%, that is not worth the extra cost to me, if someone is comfortable with that larger failure chance, there is no law that will stop them from buying what they want.