Proportioning valve question for disc brake conversion

If you are going to disc brakes, you MUST use a proportioning valve, whether it's like the factory one @Oldmanmopar showed you, OR the aftermarket one you add in the rear line. PERIOD. what's confusing about that?
like i said in the first post at the start of this thread im still learning. This is probably the biggest thing ive done on my dart besides replacing all old drum brake components in the rear. So my bad if i sound dumb haha.