Most companies rely on increasing the size and scope of perimeter defences for their security – a bit like widening the moat around the castle or building higher/thicker walls. However, the more difficult a thing is to do, the less likely they are to do it. Bad guys out there are not attacking organisations for fun, theyre doing it for commercial gain. The ‘serious’ bad guys are only interested in one thing breaching your defences. They can devote time and effort to this single purpose – but only to a point.”]
Source: https://informationsecuritybuzz.com/articles/security-layered-approach/