@pete-s said in Password Managers:
Because you don't know what they do with your master password, encryption keys and other things.
Last I seen, LastPass doesn't have your master password.
LP stores a hash of your email address and master password on your computer (not its servers), which it uses as an encryption key to encode your log-in details for other sites (with a 256-bit AES cypher), before storing them on its servers.
They don't know your details or encryption key, so create a unique ID token for you by hashing your password and local encryption key together. That ID token is then hashed with a random number when you create your account.