It’s true. I’ve bought power 5V 2.5A power supplies for $20 and they work fine … cheaper ones are garbage, they can power flash drives without a problem, but hard drives virtually a no go. The ‘unstable’ 5V 2.5A i have can only handle a 314GB WD Pi Drive and that’s it.
have never tried booting from hard drive … i’m happy with SD Card Booting as it’s Fast, and i can swap out the SD Card with different OS’s
Anyways, have been using a WD My Passport Ultra 4TB with my Raspberry Pi 3 directly connected via USB (no USB hub) for years now (also works fine with a USB Dongle for Keyboard/Mouse Combo) … in that time not one single problem. Has worked perfectly.
Have never used one on the Raspberry Pi … but i have seen a powered USB hub back powering my PC even when it’s completely shutdown, which i wasn’t keen on.
