>When isn't it?
When it's time. Or skilled people. At some point there are not enough LeBron James' at any price to fill out the size roster one wants. At some point there is no physical way to spend X hours on a thing for X large enough and enough things.
So showing that money is putting a definite upper limit on a thing shows one constraint is money. It's entirely possible there are not enough people on the planet to both invent novel things and validate those inventions as novel, for certain classes of things. So I suspect in patenting, there is also a shortage of experts capable of validating a thing. I know for some patents I've been involved with, at some point in the process there was likely not another person on the planet that would understand what we/I did because sometimes the edge of knowledge is completely esoteric and the domain of one person.
Heck, there's very important math proofs right now that have gone unvetted for a decade despite all the world's experts working on it, having entire conferences and workshops dedicated to it, and they still cannot come to a conclusion about the work. I suspect such things happen in other fields as well, including patented things.
So, in a situation like that, time and/or people is the limiting factor.
>If they need more money, then they should request more.
What they view as their need to accomplish what they want to do need not be what others want them to do. They also might make the request knowing more about how their budgetary process works than outsiders.
Overall I'm fine with the system as it is, taking into account the difficulty and increased costs it would entail to make it significantly "better."