Blurbs in black and white

Blurbs are on my mind, as we are seeking them for my next novel. I'm thrilled to report we have a great one so far. I'm grateful for any author of any race who takes the time to read my work and lend their name to help out. But the process has got me thinking. This blurb is from a white author. My first novel also had blurbs from black and white authors. A quick look on my bookshelves finds Stephen King blurb My Soul to Keep by Tananarive Due; Dorothy Allison blurb The Untelling by Tayari Jones; Jill McCorkle blurb Ugly Ways by Tina McElroy Ansa. First question it raises is: Does it matter to white readers to have a white author say, "hey this is a good book"? Second question is: Why? Third question is: Are there white authors who have blurbs from black writers? Maybe Walter Mosley, Alice Walker, Toni Morrison. Anybody know?