“use a strong password” whats that gonna do if the database gets pwned, sandra?
Strong passwords aren't intended to simply protect against brute-forcing a password via trying to authenticate repeatedly, but also to help protect against brute-force attempts to obtain passwords from a compromised password database using a dictionary attack, the scenario you're describing.
Typically
if an authentication system is storing its password database competently
the password shouldn't be stored in plain text. Instead, the password will be salted (to avoid rainbow table attacks) and then hashed via a cryptographic hash. The password database entry will look something like a tuple of (username, salt, salted hashed password). If the password is a strong one, it will be computationally-hard to obtain the plaintext password, even if someone has the salt and the salted, hashed password.