Makes sense. Do you have any particular implementations in mind that work this way?
I think this depends on the random number generator. For a counter-based RNG, the "internal state" is just a counter, so adding 1 or 2 would result in reusing random numbers in different streams.
The complexity is because it is not a cryptographic pseudorandom generator.
If you have something cryptographic, than any basic operation on the internal state (ie. Increment by one) is enough to totally change the output stream in a way and outsider cannot predict.
