Do you have any idea of the kind of work you are demanding? It's fairly obvious that you are strongly biased here, so there is probably no convincing you, but let's try to take this into another domain which may be more comfortable.
Let's imagine we're talking about, say, performance. One individual has undertaken to provide a review of another's work, though it is of no benefit to them. Looking over it, they point out several sections and say: 'I think this technique might not be too good. Perhaps you could research this bit and see if you might improve it. Right now it would cost me a lot of time to look into it for you myself, and I could well be wrong, but I hope this pointer is of some use'. Is that FUD? 'He pointed out an area which looks suspicious, but didn't fully analyse or benchmark it! That monster!'.