> This means a connected external power supply will backfeed the computer and that could be a recipe for damage to the port or the computer and is something we had known about causing issues over 20 years ago, yet we’ve still got designs with this issue today.
On the other hand it's useful for space constrained embedded projects. I got a small outdoor enclosure for a Pi Zero, to which two RTL-SDR sticks are attached - too much to supply via the Pi's USB-OTG power rail alone. With the Adafruit microUSB OTG hub [1], I now only have one power supply going into the hub that backfeeds the Pi Zero... one cable less.