If an app has root (which it would need to write to /usr), then mount -o remount,rw /usr Can defeat that pretty trivially. Probably why nobody really both

If an app has root (which it would need to write to /usr), then mount -o remount,rw /usr Can defeat that pretty trivially. Probably why nobody really bothers with it. /usr (and root access in general) is such a distraction from the real issue though, which is that all the stuff I care about is accessible under my account. My browser data, photos, etc etc… if a malicious app isn’t sandboxed and is running as me, it’s game over. Stopping it from writing to /usr (or other places outside my homedir) is basically meaningless.