I won't disagree with any of the above. I thought the exposure to other dogs was the really important part of dog obedience training, then found myself avoiding other dogs and training my dogs to ignore other dogs anyway.
Just a regular pet guy and my first dog attended puppy class where I found out he was an A hole but we made it through, then my other dogs no formal training. I knew what I wanted in my guys and have had few problems getting there.
My GSD was the one exception people issues that was new to me. But I did the Leerburgh "Who pets my puppy" and he turned out great. Did not do that with my Boxer and save for other training she would have happily driven/rode off with a stranger!
My first dog convinced me to avoid dog parks with him and I think in the long run that's been a blessing my guys have not had any issues that needed addressing. So I guess I'm happy going it alone.
But you have to start somewhere with your "first" dog.