It's because there is an overvaccination problem where some of the vaccines are unnecessary unless you're sending your dog to a kennel or any environment where there a lot of other dogs.
The rabies vaccine is necessary and is lumped in with the unnecessary ones. Has to be all or none for them
Your dog really needs heartworm protection, flea and tick protection, and the rabies vaccine. If you're keeping the dog at home you really don't need the rest for a majority of cases.
We mostly keep our dogs in the backyard. They aren't around any other dog feces but their own.
But yeah if you take your dogs to dog parks or a lot of walks with people who don't pick up after their dogs (gross). Sure, vaccinate with that.