A lot of these people grew up being called “The Black Kim” or “The Fat Jessica” because there are only so many standard names. Think about what that does your self esteem? All of your experience is summed up as “Fat Jessica” for the entirety of your formative years.
Further, I am one of 15 people in my company with the same first name, and 3 of which have the same first name, last name. I spent easily an hour per pay period forwarding emails to the correct parties.