All dogs should know how to act in a social setting. Unfortunately, many dogs never get out of the house or apartment so they never meet other dogs and people. Puppies should meet and greet as many people every day as possible otherwise they may grow up never mingling with others and not know how to act. They may become overly protective over the humans in their life and become aggressive towards people and other dogs. Proper introductions to people and other dogs is the responsibility of the pack leader and should be done only when dogs are in a calm state of mind.
Good Pack Leadership