I think I understand, but I'm not sure how that actually helps solve the issue of regular people with famous names being mistaken for celebrities. This is a case where everything you mention was in place (and even though they could change the text and photos that didn't happen), and still many many people were confused.

Some account handles will match real names. People make assumptions on that. At the current time, no matter of locking down profiles so they don't change will solve the problem of people assuming an account name must match the famous person with the same name, because names are not only not unique, collisions are common enough that famous people share names all the time. People don't do the barest amount of verification of what they are seeing compared to what they assume, so nothing you add that they have to look at to fix that will actually fix it.