I think it depends on the dog and the skill of the owner to handle the dog.
We have a pit bull/ bull terrier mix. He has been going to the park since he was a puppy, but when he became a big boy and realized he could handle himself, he did. Never started a fight, ever, but he grabs an ear or the side of a face and won't let go so the other dog can't attack him. No blood, no shaking, ripping or tearing. He just puts a stop to it.
He also decided he didn't have to listen...he was off leash and it's not like we can catch him. Enter the shock collar. No more issues. We can't control other people and their dogs, but we have control of ours.
During one of those disagreements, another dog attacked ours. Frank pinned the other dog and wouldn't let go until I got there to separate them. The other dogs owner thought he was going to beat my dog with a collapsible baton and told me he was going to have my dog confiscated and called the park ranger. Witnesses were on my side, his dog attacked mine and Frank was defending himself and I still have my pooch.
So yes, people are that way. All you can do is train your dog and slowly introduce her to other dogs and people. Even as she adjusts, she's not going to like everyone/everydog she meets. You don't need to visit a different park and that guy was an ass. She'd had an iffy experience prior and I can see how it might make her a bit wary going into the next meeting so soon afterward. Try again!