Okay as a breeder a topic near and dear to my heart. And let me say outright that this is just my personal opinion and does not represent any breed club I am a member of or AKC or CKC.... so have I set enough qualifiers....
First the word Kennel affixed to a breeder I don`t know, would give me some pause.
Then I would ascertain exactly what type of dogs they are setting out into an òutside kennel if indeed they were.
Quite frankly for all toy breeds and some working breeds and some hunting breeds, I would say outside kennels are far from the best.
These breeds truly do need inside socialization. That kind of can happen as a matter of life in the house. Of course coupled with neuro-stimulation, planned socialization, leash training, grooming experience et al.
What happens in a homeÉ Well the vaccum cleaner goes, the coffee grinder, maybe a smoke alarm, toilets flush, showers go, phones ring, doorbell goes. Food is prepped (and all dogs love food prep)
ppl walk up and down stairs. Humans laugh, love, and just interact with one another. Hey guess what that is the life of a `pet`puppy who will be sold into a home.
And even if you are a show breeder, most of your litter will go to pet homes. So all puppies IMO should be exposed to what a home is. And quite frankly they can`t get that from outside kennels; even if you set aside an hour or three a day to socialize into the home.