They're not wrong, this is because of users re-using passwords and an unrelated hacked database being used to brute-force access to 23andMe by checking to see if users re-used passwords. Shocker, they did.
I'll ask a question: What is a security system supposed to do when provided with the correct login credentials?
Hopefully it will inspire more companies to force 2FA, like 23andMe is doing now. That's honestly the biggest part that is their own fault, not forcing MFA from the get-go on their customer base.