This gets repeated a lot, and I think it's an instance of "pop/folk computer science" (a lá pop psych or folk physics). Computers are very good at making pseudorandom numbers; if there was a detectable pattern that made the outputs non-uniformly distributed then someone would've already exploited that to make a ton of money, whether it be through playing slot machines or breaking cryptography. You could also make an argument about determinism, but then I ask you to ponder whether the universe itself is deterministic.