The reason why they measured impact in that way is because that's what most funding agencies today are speculating in for their decision making processes. And as data shows, most funding agencies are getting it wrong.
ITER, Wendelstein-X, LIGO, Planck, I could go on. In all those cases any results happened >10 years after the funding started or might still only happen in the future. In the case of the LHC, but also many other Detector experiments individual grants to research groups were typically (not just anecdotally) way beyond 700000€.
According to wikipedia the project costs about $9B, but I doubt that includes all supporting efforts and researcher salaries. That would fund 12 thousand of these smaller $700k projects.
If we first invested in research to make building the LHC cheaper, we'd get more benefit for less cost. That's the only reasonable criteria for allocation of resources.
Also, I love your username :)