Someone would need to know what accounts you have (which are not stored on my email)
Aren't they?
Access to your emails means access to your messages. If I see you get a lot of Amazon email, I can reasonably assume you have an Amazon account.
Most services send you emails at least on registration.
then know the password to access them.
Nope. Because I have your email account. And the usual method for resetting a password is via an email sent to your email account. That I've already compromised.
That’s if they are able to bypass the 2fa I have set on each account that offers it.
That last part is a pretty big asterisk. Sites that offer it are in the minority still. That also assumes your 2FA method isn't email.
And it’s also too bad for them, because I use different email address per account, which can be rotated and changed (if the damn site allows you to update your email).
You do realise the average person will never do this, right?