"Gives hackers a head start in accessing online banking or PayPal accounts linked to the same address" != "there are online banking systems out there which rely only on an email address and password for login creds"
However, to take your point at face value, yes PayPal only requires an email address and password as login credentials. You can then make payments from that, which are linked to your bank account, and remove funds from there.
To discuss what was actually written in the article, before you badly paraphrased it, as a real world example Egg credit card requires the following login details;
First name, surname, date of birth, postcode, mother's maiden name and password.
Assuming you can access a user's webmail account I suspect you've got a good "head start" to finding their first name and surname (read a selection of emails till it crops up). From there if they have a facebook account linked to their webmail address you might be able to get their date of birth. Which just leaves a postcode to find. Figure that out for yourself, but it ain't that difficult.
So no, the article's not fast and loose with the truth, you've just misinterpreted it by not reading it properly.