I also agree that early handling and other people, voices, movements are great. We had one couple at the vet's office when they got their tails docked and dew claws removed (Rotties) and they visited the puppies 2 to 3 times a week til they took their pup home. LOL and then brought him over to visit almost weekly til we moved to GA.
I do consider some people risky– particularly if they foster younger dogs, have a puppy at home, work for a vet. I know the vet thing seems odd, but I have had 2 friends get parvo in their home from visits by vet techs. I have also only had 2 rottie pups I placed get Parvo-- BOTH owned by people who had vet jobs (vet tech and vet student who worked at a vets). Yeah, you can tell them go home, change clothes, take shoes off at door. Both claimed they asked them to and had them remove shoes outside. I don't foster with puppies in the house either just to keep stress lower. But humans... I consider it a boon. I have mentored new folks to the breed by having them come HELP with whelping.
Long ago, with my first litter, I didn't let them OUTSIDE til they were 6 weeks old. Yes, I lived in an apt and we had flea issues where you could see the fleas jumping even though they sprayed so often and so much we were toxic. But the truth is, I didn't want my 2nd litter outside either and we were in our own home, isolated yard and fencing. Fortunately MY mentor chewed me out, talked about how the more varied experiences they have young the better, and I changed. Keep in mind these were Rottweilers, but it isn't different for any breed. More experiences are good.
If the breeder is giving them lots of experiences and only limiting strangers, not an issue though I would obviously agree not in any way necessary. You might ask if the breeder is getting a lot of contact with people in her family/friends etc and simply limiting others. I also know a breeder who won't let potential owners see the pups til she decides where each pup is going as she said she got tired of people visiting early, CHOOSING a pup they wanted and then bailing when she decided that pup needed to go elsewhere.