If Chrome were to hide them in the UI, you could still get to them one way or another (like grabbing a memory dump). If someone has physical access to your comp

If Chrome were to hide them in the UI, you could still get to them one way or another (like grabbing a memory dump). If someone has physical access to your computer when you're logged on, you've lost the security game. There's no point in adding a layer of obscurity on top.