I think the allure here is the same as with ciphers. Everyone can create a cipher they cannot break, but cryptographers can break easily. Likewise, it's easy t

I think the allure here is the same as with ciphers. Everyone can create a cipher they cannot break, but cryptographers can break easily. Likewise, it's easy to invent another PRNG, but not so easy to figure out that, say, its output always falls on one of seventeen parallel planes when treated as consecutive (x, y, z) coordinates. If you want random numbers that are fast and almost-cryptographically-strong, you can take some ARX block cipher and reduce number of rounds as you see fit. But it's not nearly as much fun.