Sounds like a sensible reason for using accel, provided you wouldn't do better out of improving consistency in other ways or with a mousepad catering to the needs of the game. If it's indeed working well for quake players then maybe it's to do with reaction times in quake. I'd prefer upping the polling rate as a way of solving that.
As to low sensitivity in quake I'm not sure it would be the right choice or wrong choice, as I've only played some quake clones and using a medium-low sensitivity (which seemed right at the time). A lot of games low sens just works so long as you improve other habbits like being cautious, cornering properly (in csgo) being more aware of surroundings, making sure you can still do a 180 and some reasonable headphones.
I think most people should prefer some more exacting methods to improve consistency further like a high refresh monitor, framerate caps within the spec of the monitor and stable mouse polling rate 250Hz-1000Hz for improving consistency beyond just disabling mouse accel or other built in annoyances.
I'm also unsure all the details in the gsync/freesync argument but I have an idea I wouldn't want either the frame rate or the refresh rate jumping, wether it jumps up or down is not relevant because an upward jump means you get more movement out of nowhere. It may be smooth, but I guess the better solution is either get a 250Hz monitor or wait for them to be mainstream.