This is the KEY point.I'm pretty much my mini Aussie's whole world, he does everything with me but he still benefits so much from interacting with other dogs, idk if you've ever heard a dog laugh before but they pretty much exclusively do it with each other when they play, there's so much to dog's social structures that I will never be able to completely replicate. I'd compare it to living in a country where you don't speak the native language, of course you can communicate and learn the language but there's just something about speaking to someone in your own native language who shares your culture that makes you feel a little more fulfilled in a way.
At the end of the day you're a human and your dog is a dog. You're separate species and you can NEVER truly understand your dog and their needs inside and out cause you simply are not one.
This goes for all social animals, not just dogs.