Why did crossbreeding become taboo?

Attention is called to the "commitment among the scientists and at the Nordic kennel clubs when it comes to using the full range of breeding tools to counteract narrowing gene pools and impaired health in vulnerable breeds" --  "Progressive breeding programs where crossbreeding is included".

Cynological organizations, Kennel, and Breed Club rules and regulations as well as breeder attitudes and mindsets focused on achievement in the conformation rings pose significant challenges to sustaining genetic diversity in breeds since the closing of studbooks occurred. The viability of breeds and their management is under increasing scrutiny as evidenced by declining purebred dog registrations and a public perception that inbreeding of purebred dogs has lead to poor health and unstable temperaments in some breeds. The rise in popularity of "Designer" breeds is a subject of much consternation among members of the purebred dog fancy. And yet... "If there are reasons to believe that a breed suffers from severe and frequent health problems, due to a narrowing gene pool, it must be a moral duty for Kennel Clubs and breed clubs around the world to act and to act fast."

"From a longer perspective sanctioned interbreeding rules for recurrent crosses between defined cousin breeds, must be a relevant option to give concerned breeders a permanent tool to keep genetic diversity on a sustainable level."

Article in Finnish...

https://www.katariinamaki.com/l/milloin-roturisteytyksista-tuli-koiranjalostuksessa-tabu