Comment by dfox
12 days ago
Pin 9 is there to power the EEPROM in the monitor fromthe computer even when the monitor is turned off, so monitors providing 5V there would lead to same kind of problems as there are with DisplayPort pin 20 and cheap cables that connect this pin through (which would be correct for DP 1.0, but there are no DP 1.0 products).
Exactly. Back then we didn't imagine we would want to power a small dongle out of a monitor port.
Sadly, when people invented HDMI, that was a lot more obvious.