As it is, if she finds out that she’s a mismatch with Yosef, she knows he’s a carrier. The only difference is that she doesn’t know which specific condition he’s a carrier for. Do you think that this distinction is so important?
FTR, I don’t think the policy is for nefarious reasons as Dash’s cynical side does, but I definitely agree with Dash and writersoul that the effect is a monopoly. That’s not necessarily a terrible thing either, because at the end of the day, we have a relatively economical and efficient way of avoiding mismatches.