The above postings show that there are many people opposed to dogs in general and large dogs specifically. Much of that is justified, but generally because of the dog owners rather than the dogs themselves.
You will have problems at some parks. You will just have to verify in advance whether they have a restrictive pet policy or not. And please be a responsible dog parent at the parks you visit. Even "friendly" dogs can suddenly lash out at another dog, or even a person, under the right conditions. Large powerful dogs are a particular concern. That is what scares some people.