You don't if people are any competent and ask for an email in scope or ask you to enter a password with username later. That way, you have access as long as you

You don't if people are any competent and ask for an email in scope or ask you to enter a password with username later. That way, you have access as long as you have access to your email/password. It is great because the friction to start using the service is low but you can add additional stuff after you know that you want to use it. Few services do exactly this. They will lock down your account and ask you to add a password after a day.