GDI was always at a disadvantage, especially on maps with no base defenses. SBHs would inevitably get in without too much trouble, and their constant beacons would force your team to continually attack and defend at a steady pace. Nod still has their worries, but at least they don't have to worry about invisible people walking into their base.
Also, old Renegade's arty was even more powerful. There was literally no way to stop a well-supported column of them; which made games such as Field extremely unbalanced and one-sided at times. GDI could attempt to push out with 7 mammoths and they'd be flash fried in almost a blink of an eye due to the sheer damage that the arties are pushing out.