This seems to be the big societal discussion, in the same way that people blame banks for them sending money to crypto and romance scammers overseas.
I think this would be far more akin to finding out someone has stolen a card number, which has happened in breaches, and used it to purchase a lot. Generally, we do expect recourse on the bank's end.
If someone gives their routing number and checking number to a scammer, that is also considered "using the platform in any way other than intended". In 99% of cases, you'd be providing that information to someone you had an actual business relationship with. My employer, for example, might have that info in order to process my direct deposit payments. A debtor may have that info in order to process ACH payments. Giving that info to a total stranger would be an issue but that wouldn't be the bank's fault. Neither would it be the bank's fault if you chose a poor or reused password.
That's what happened here. Users shared data with total strangers who requested their connection to their DNA data based on some percentage of shared DNA. Users accepted those requests. The users who reused their passwords had all their info accessible. The users who accepted sharing requests with those users had their shared info accessible. Both cases are "using the platform as intended".