Corrected.
Everyone would still be able to do what they could do before, just that you would no longer be able to instantly be back in the action, and probably spawning in whatever building is under attack, which makes defending slightly less effective. Offense already has numerous disadvantages in RenX/OldRen, especially in AOW. If a team is decent, AND campy they can make a game go on for hours on end. This is only one small part of that however.
Besides... if you're already defending in your own base.... you can just exploit another really poorly designed feature in Ren and just refill spam indefinitely.