I agree with you in general (you can't get wet from the word "water"). In my experience, though, if you're building something fuzzy, it usually turns out to be a complete waste of money with no results. Human beings seem to need reasonable narrow scope to produce something useful. So while the team doesn't need to waste time on formally defining "intelligence" in a way that completely captures all its aspects, they do need to precisely define what they're building, to some reasonable degree.
Without a scope definition they can't budget their funds, their time, and their human resources. Projects like these usually result in a waste of money with nothing to show for it. Of course if they try to define what they're building, it will be intimately linked to the definition of "intelligence" (assuming they claim they're building an intelligent machine). Then someone will come along and propose a counterexample that demonstrates how the machine likely isn't intelligent at all, and cannot perform well on some problem where humans do spectacularly, thereby shifting the team's scope and definition. And so, they'll be back to square one.
Without a scope definition they can't budget their funds, their time, and their human resources. Projects like these usually result in a waste of money with nothing to show for it. Of course if they try to define what they're building, it will be intimately linked to the definition of "intelligence" (assuming they claim they're building an intelligent machine). Then someone will come along and propose a counterexample that demonstrates how the machine likely isn't intelligent at all, and cannot perform well on some problem where humans do spectacularly, thereby shifting the team's scope and definition. And so, they'll be back to square one.