It seems to me that it's the link between those two parts that is problematic! If someone sold genetic tests that just output a list of markers, and the clients

It seems to me that it's the link between those two parts that is problematic! If someone sold genetic tests that just output a list of markers, and the clients consulted publicly available literature to discern the meaning of those results, then no one would have taken the responsibility of giving advice to a client. By packaging a specific, curated set of information with the test results, 23andme has crossed over from offering tools to offering expertise - and has therefor taken on responsibilities.