[mothered]

in case the user uses the same password in diferent services. It will be possible to crack a mega.nz account for example.

I can confirm that It's a commonality for users to use the same email/user/password for most, If not all of their online accounts.

During my tests (and believe me It's In the thousands), I've established that around 70-80% of users use the same credentials. Just the other day, after compromising an online shopping entity and obtaining user logins (for that site), I tested them on all major websites and the majority authenticated.