Professional Historians, of course, will not be able to make a living if they write only in total agreement with that which their predecessors have written, this is the basis of much "revisionism" (ie Publish or die !)Their theories on historical facts are of no more value than those of anybody else who has researched. We have no need to be in awe of them.

Some make a living pushing the old version of history.
Their books are the best sellers.
We are told that revisionists have long been the majority.
We should not be in awe of them, but neither should we dismiss them as Jim does.