[AlchemyMG]

Its not absolutely vital that you do it, but if you're already in the process of bleeding its just an extra step to ensure no bubbles got trapped in the ABS circuit. If you're flushing the system and it was bubble free before, there shouldn't be any bubbles induced as long as you keep the reservoir full and it doesn't suck in any air.

Alot of the early ABS units had a bleeder because there were some issues with bubbles getting stuck in the circuits, but they've pretty much figured that out in the modern stuff. Alot of the newer ABS units do a quick cycle on start up mainly for this purpose.

If you do have the scan tool to activate the ABS module another trick you can do is use a little handheld vacuum pump and put the reservoir under a vacuum and cycle the ABS module, this will pull any bubbles up to the reservoir where they can bleed out.
We do have an Ethos scan tool here at the shop, so we can do a bleed this way if anyone needs it done.