Yes, if the edge is whacked the crack will go only as far as the purfling. It also diffuses the force of the blow so that not as much force is carried into the rest of the instrument.

There was one luthier who competed with Stradivarius and his signature was that the purfling on the back would be swept around the surface of the whole back in a large, beautifully-inlaid pattern. Makers of his "school," generations later, were still copying this design, and Hardi has one of these models made in that style. One of these days I'll get him to write about it here, or maybe his Mudcat photo when posted will feature a shot of this.

~S~