People consistently misuse the Swiss cheese security metaphor to justify putting multiple ineffective security barriers in place.

The holes in the cheese are supposed to represent unknown or very difficult to exploit flaws in your security layers, and that's why you ideally want multiple layers.

You can't just stack up multiple known to be broken layers and call something secure. The extra layers are inconvenient to users and readily bypassed by attackers by simply tackling them one at a time.

Security by obscurity is one such layer.