In the olden days was the manual technology using microscope to detect ones blood group which technology wasn't as advanced as it's in this days.
Bearing unhealthy children such as the sickle cell didn't start in this modern days either rather and since there had come the modern technology and we're also living in the advance era with more educational personalities, we've found it necessary to avoid the accidental coalition where unmatched genotype meets in the state of partnership or marriage that may result to producing unhealthy offsprings. This doesn't mean that the genotype medical tests amongst a man and a woman became a trend in this modern days instead, we're only trying to help ourselves and secure health being for our unborn children.