Why Are Overlords Considered Defenders in Independence Wars?

This seems like a pretty big oversight, independence wars are completely broken. Overlords are considered defenders which means ticking war score is to their benefit. This is not how it should work, and it's not how it works in Victoria 3.

This means you can't just defend your lands, win a battle or two, and wait for ticking warscore to gain independence. I'm playing as a subject of Brunei with only rural locations, so I don't even have the ability to build boats and capture Brunei.

Why is independence war this way? Imagine if the Americans had to capture London or the Dutch had to capture Madrid to gain independence?