And the times I have been on standby it was back-office who arranged it not gate. E.g. turned up at lounge super early on a Flexi. No flights available until my flight. Lounge agent put me on a list. A couple of minutes after check-in closing got a SMS and the lounge page with a new boarding pass. Was carryon only.
Gate agents should be focused on getting people boarded not sorting out other issues. Look at how long it takes to board a plane in NZ vs say the US. The US seems to take twice as long for same plane size.