Why should chisels and other sharp tools not be left lying on the workbench?
Leaving a sharp edge on the bench where metal chips are present can cause it to become magnetized, picking up tiny bits of metal without you realizing it. If that edge is then used in wood, it can damage the wood and ruin the edge. Keeping chisels off the bench in a separate holder avoids this problem and also prevents them from banging into other tools and getting chipped.