Recently one of the largest companies, Facebook had a security breach in which millions of accounts were impacted/compromised, this brings to the forefront the fact that you are your own security expert in this on line world, many sites offer you the opportunity and even encourage you to sign in to their site using your Facebook credentials.
No – just No.
Combining multiple accounts to use the same set of credentials creates a single point of failure, if the account credentials of the main account are compromised there is a risk of other accounts then being accessible.
McLean Data advises avoiding this in any form, facebook, google and any/all accounts you use should have independent credentials so as to avoid security concerns, if you have an issue with one account it does not have the ability to impact others.
As a side note, not a big fan of these “remember all your password apps” and autofill them all based on one set of credentials, there are several of these apps that go by different names and are made by different companies that many people use and they potentially create a treasure trove of all you passwords if the single app is compromised. It is a pain to keep track of and remember so many account credentials individually but don’t make the mistake of sacrificing your security for convenience.