Most puppies are not over vaccinated, in fact that would be a little difficult to do since they really need that series of shots the first year. It's older dogs that often are over vaccinated and this usually occurs over a long period of time. Also, the ramifications aren't as noticeable or deadly as under vacination. There have been certain conditions linked with over vaccination, but diseases like Parvo are deadly and painful. So while it sounds good to say, I'd rather have less than too much, in all probability, it's much more harmful to your pet. It's like saying I'd rather be 100 pounds underweight, than 100 pounds overweight. No you wouldn't, while both conditions are bad, one will kill you much faster than the other.
Dr. Jean Dodds' Pet Health Resource Blog | 2013 and 2014 Canine Vaccination Protocol - W. Jean Dodds, DVM. How about heartworm medications are you all against those as well, they aren't holistic.