There is no aim to get one or zero in output. We need to have enough ones for XOR algorithm to invert bits. A xor 1 => inverted A. A xor 0 = A. So if we have to

There is no aim to get one or zero in output. We need to have enough ones for XOR algorithm to invert bits. A xor 1 => inverted A. A xor 0 = A. So if we have too few ones, source data will remain unchanged and that quickly become a pattern. The same is if we have too few zeros and amount of inverts become predictable.