A person has a form that asks for a name and password. The password is sent to the server where a hash is created from hashing the name and password. This hash is converted into a number using the ascii value. The number is limited to 10 digits, and is used to seed a random number generator. Three random numbers are generated from 1-77616. These numbers are used to select words from a list of 77616 English words. The three words formed are used as the persons username.
77616^3 is roughly 2^48, so the probability of a collision after a million username generations should be ~0.001774778278169853.
Does this seem like a secure way to manage users, that way a login/register system doesn't have to be implemented? Is there any benefit of using this kind of system over a traditional login/register system?