MBR is so easy to understand. UEFI, has so many things to understand EFI, ESP, MOK, signing procedures and signing chains, ... it's just so darn complicated.
Yeah, if you have only one OS. Or when you have more than one, but the other one doesn't constantly try to fuck up the first one.
MBR is easy in this regard. Windows never touches the MBR magic, even when updating, so it's all good. GRUB keeps the MBR in check, Windows doesn't meddle, everything's hunky dory in MBR boot land.