This is a tough question and really the answer depends on what kind of dog your dog is playing with. Is your dog well socialized? Is the dog your dog is playing with fluent in dog language?
Most dogs love to play but some never learn to communicate well with other dogs. This leaves a lot of space for misunderstandings. Giving your dog the opportunity to make mistakes and learn as a puppy with forgiving adult dogs will allow him or her to learn what certain postures, expressions and movements mean. This will also give him a chance to learn where most dogs keep their boundaries and where their bubbles break.
Isolating your puppy is like not allowing a child to go to elementary school and then expecting them to be normal when they go to middle school. Don’t fall into the trap of thinking that your puppy can’t go outside until the shot regimen is over – they are safe once it is started. When your dog is playing with a dog that ‘went to elementary school’ then you will know that this dog has a better grasp of how to play and what the rules are. If your dog is playing with a dog that never ‘went to elementary school’ then I would be a lot more cautious and step in if I saw anything that made me nervous (showing teeth while barking, relentless neck targeting, any excessively quick movements, etc.). It is not your dog’s job to teach un-socialized dogs how to behave.
Dogs that need help with socialization do need exposure to more dogs that will play with them. Their owners need to be proactive and find other dogs (with understanding owners) that have clear boundaries that they will benevolently enforce. Usually older female dogs have no problem telling other dogs “This is MY space.” The key is watching to see the under socialized dog give way to the older dog. If the older dog stops and growls then the other dog needs to respond to that by looking or moving away. If there is no response then it becomes stressful for everyone and you need to intervene by having your dog move away. Once things are calm again let them interact and see if any learning has happened. If there continues to be no appropriate response from the dog learning manners then the exercise should end. It is unfair to the older dog and you risk pushing the older dog to actually bite, something no one wants to happen.
What do you think?
What has your experience been?