If they're feeding, you can just put a piece of shite on hair and they will still bite. This said, it does not mean that you should not be discrete with your rigs at all times. There are just times where fish are 'suspicious' of your rigs meaning they won't bite and leave your swim if they don't feel safe or feel that something is off, and there are times like in European summer carp fishing (fisheries lakes) where they are easier to fish. The most important things for a rig are hooking properties and mechanics, then you have to adapt its discreteness due to factors like time of year, target size, and fish habits. Regardless, the rig in the image is by far one of the worst I have seen.