Don't mistake the term pseudo random number generator for meaning not-even-close-to random number generator. For all purposes aside from incredibly demanding monte carlo simulations and cryptography PRNGs can be thought of as perfectly random.

The most common PRNG has a period length (number of runs before it will repeat the sequence) on the order of 10^6000.



Nothing in an MMO will ever even come close to pushing the limits of 'randomness' for any recent PRNG.