Someone else in this thread mentioned a company that has customer service type in your password to open your account. So that would be a non-plaintext reason to insist on non-obscene passwords. But it's still terrible, because why the hell is customer service typing in your password.

Pretty much all organizations that allow phone authentication seem to be at risk of engineering attacks. The only ones that manage it send you something verifiable they can ask about like a credit card, and people who really care like the government just send an actual human to your house.