The problem with that is that it gives a change tracking tool that doesn't work, giving people a false sense of safety, relying on users to remember to manually diff every change sounds like a security issue in itself, that diffing should be either an automatic process instead of track changes or track changes should track everything by default.
If the other party attempts to sneak in such a change, usually you extract a concession from them when you catch them as many bar associations now regard that as unethical behavior warranting discipline.
Yes, but you still have to catch them, and the fact it's possible gives them the leeway to try, when the point of business is to do business, not to catch people out.