It isn't true though. C64 PSUs would fail high and fry downstream chips and passives. Amiga PSUs are designed to fail low, and with the exception of some exceptionally rare faults, they won't fry your computer if the capacitors fail
It fried mine, twice in a row. Lost the A600, which came with A1200 PSU, and then an A500 to a different PSU. Additionally, the second(ary) issue with A1200 PSU is it's barely strong enough to support the base hardware configuration and will make expanded systems unstable.
That is definitely a Commodore tradition. I had a C64 back that had a PSU die in 1985 and took out all of the DRAM chips.