A Houdini fetus here. After watching the various, albeit rare (kudos Horikawa), channels on HOW to use such a beast... no one explains the WHY.
Why is the ampersand so critical in parts of the Vex world? Clearly, a wnoise vex function cannot be fully utilized without accessing the ampersand feature.
I would be grateful for a deeper explanation.

if you are talking about the docs, & just means that the argument variable with & will be modified
not really sure if it's just manually put in the docs or it was automatically analyzed from the code, since in VEX all arguments are passed by reference and therefore in theory function can modify any of the arguments unless it's const

so in case of:

the function will not return anything directly since its void
but will modify variables used for seed, f1 and f2
which can be also thought of as it returns 3 values: seed, f1 and f2

Very helpful. Thank you.