Earlier quoted context omitted.
$y + $z must be greater than $x. If $y is money and $z is scientific contributions... $y is most likely not something people are offering money for. So in an open market its value is at or near $0. So $z by itself must exceed $x. To not care about the $z, $y must exceed $x by itself and that seems really unlikely for the types of things that OP suggested instead of proof-of-work.
>If $y is money ... $y is most likely not something people are offering money for. scrathes head
I think I was trying to be too smart and I got my variables confused.