But it can never be used to boot homebrews. There's absolutely no chance of that ever happening.
(The bios bootup code which looks for bootable files on MC is no longer present in the new bios versions.)
So for booting a homebrew at power on or reset on such a console you need to use either a modchip, or a boot disc intended for that purpose, such as "SwapMagic".
You could also use some old methods of swapping between original game discs and a burned homebrew disc, but those methods are very destructive, and likely to kill your CDVD drive long before its natural death.
Best regards: dlanor