I'd argue it's pretty important for working dogs too, especially ones that require specific temperaments for their jobs like border collies, livestock guardian dogs, and pointers.
Anyone can lie and make fake paperwork. DNA is just that second check to have a much better read on the truth (assuming they don’t mix up the samples).
Honestly, I’m not a breeder or a dog enthusiast though. However, I do love my shibas even if they may not exactly be pure bred.
Litter loading is a thing. People buy a dog but it's swapped for a cheaper or non pedigree. DNA testing is done for puppies to verify that they are what they're supposed to be and AKC requires it sometimes.