A private key is supposed to be generated using cryptographically secure PRNG to make it impossible to guess or reproduce by an unfortunate accident. In most cases, the passwords that users generate for different websites aren't as secure as a random 256-bit number, which means encrypting them into a private key only makes your coins vulnerable to a hacker's attack because low entropy takes little time to reproduce in case specialized software is employed. When dealing with cryptographic keys, avoid human brain-generated data at all costs because such a practice doesn't allow cryptography to reach its full potential in protecting sensitive data. Any cryptocurrency project that promises you to make a secure wallet using "convenient" data is likely lying and probably wants to steal your crypto because cryptography is not about convenience and making everything human-readable, it is all about security and robustness. Don't fall into the scams like that, follow standards instead because they were thoroughly tested and proved their reliability.