they aren't industrial embedded computers, so comparing them to some $1500 hardened industrial embedded platform is not only unfair, it's not a comparison that's respectful of the other participants in the conversation. you're relying on people not knowing about embedded hardware so that it appears your comparison is fair.
The Raspberry Pi is not an embedded platform in the ways that you are using for comparison. The Raspberry Pi is an educational platform.
it is very hard to know if your raspberry pi issue is power related if you don't do what you can to make sure that power isn't an issue.
prior Pis didn't log when they had power issues, and current ones do, if they are able to.
on a Pi 2 A (I think) I had to hook up an oscilloscope to catch all the tiny power problems I was having, and only then realized what was happening. I was 100% sure I was delivering enough power. I was not. those symptoms were only visible without the scope as weird errors in the OS and running applications, and corrupted SD cards.
And you basically outlined it: they are bad quality and we have all these power problems and here's the insane list of workarounds.
Incidentally I ran mine of an Agilent E3614A which was worth 30x the price of the Pi.