Brings skeletons out of the closet. They were already there, but now you have to face them. It can be a great tool for finding out what you didn't know about your bloodlines, but it takes a steely heart to face up to what you find. It also takes great dogs to breed close as you are fixing traits fast and hard. The closer the breeding, the better the two dogs must be to make it worth it. Call weak inbreeding linebreeding if you like, but breeding dogs closely related is technically inbreeding (although there is a good argument to seperate the two), as the point is to double-up on desired family characteristics by doubling up on the desired genes. But most everything recessive in the family eventually pops up, good & bad, when line-breeding over generations, so eventually blind line-breeding leads to the same bottleneck as intense inbreeding; it just takes longer to get there. The bad news about inbreeding is that the homozygous sought may be found. In other words, you are trying to double up on genes for good heads or strong hearts, but also double up on the genes in the immune system & that can lead to inbreeding depression. So be careful what you wish for when inbreeding, especially repeatedly &/or tightly