Except in this case Johnnie and his ancestors haven't had cake for 250 years, those ancestors were violently kidnapped from their homeland (where they had plenty of cake) untold generations ago, and even after Johnnie's family was theoretically given the ability to eat cake they had to struggle for decades before receiving legal protection to have cake and even today have fewer and more difficult opportunities to eat cake than other people simply because of the color of their skin.
Are you arguing that Black Lives have never mattered? ---