However, you present an interesting point of view. As someone who remembers being able to visualize but is no longer able to.
And while I feel you on the MRI thing, I don't think you could have known you'd lose the ability to visualize. But I think there would be some value in comparing you against people who both claim to be able to visualize and those who claim to not be able to. You would serve as a sort of marker. Someone who we could be relatively comfortable categorizing as you have distinct memories of being able to visualize and now have a different experience.