As with so many other things, it only takes one. Guessing your password is the proverbial foot in the door. It opens the system up to even more stolen accounts. They'd never guess that. And if I know it, so does somebody else.
Exotic words are still words.
I'll use a word from a foreign language. More are being created every day. The passwd command will change your password. It first prompts for your old password and then for your new password, neither of which will be visible as you type. It then will prompt you a second time for the new password to make sure that you've entered it correctly.