Although I don't believe that a personal vision can ever be understood by someone other than its seer. We all interpret things differently and the way we do that makes us unique. It's like going to a funeral of someone influential in a friend's life and saying you understand how they feel. You do not. Although you probably have a sense that they are going through something hard, and you may know the general confines of their hardship. Everyone's got an opinion!
Yes, a personal vision can be really shared, because a person can agree with some or all of that vision. A person with a similar vision can help and work in the same direction. This is true even if there are small disagreements as to how that vision should be carried out.
Even when working under the constraints of financial limitations or things like the motion picture studio system, filmmakers, painters, and artists can definitely share their personal visions. They can give us access to their hopes, dreams, and what it's like to be in their shoes. This is especially true of an established talent. If J.K. Rowling wanted to write a profoundly uncommerical book that was simply her personal vision, she could do so, on the strength that her name would sell books.
I believe personal visions can be shared and I believe this happens a lot in our society. I believe a lot of novels and stories do just that, they relay the visions of the writer to the reader. I think this can also be done in other documents, such as business plans.
I do not think that a personal vision can every truly be shared. First of all, we do not know what brings such visions to some people. And we do not know if they are even accurate. Some people may have visions due to some other outside sources that we don't know about.