I had an ex with serious trust issues. On at least several occasions they tried to get into my email account. This was back in the flip phone days, but the concern is the same. The Yahoo approach seems like the perfect setup for that sort of abuse.

Assuming one has a smartphone, they don't even need the password to login. They already have access to your mailbox.

If one doesn't have a smartphone, then they need to first find out your email then try to login. By the time that is figured out you might have disabled it by logging to your account from somewhere else.