Do all black people do this, or do some do this? Ever had salmonella? Lol. It is the case that bacterial pathogens are not found in unaltered muscle tissue, but are common on the outside layer of meat. It’s also true that cooking does not remove or render the toxins ineffective (think botulinum) even though the temperature has destroyed the organism. I suspect this practice is cultural memory of a time when food sources were less regulated and more likely to have substantial surface contamination.