That probably helps more if the problem complexity is increasing linearly. If it's going up exponentially with problem size, especially if complexity increases

That probably helps more if the problem complexity is increasing linearly. If it's going up exponentially with problem size, especially if complexity increases at a faster rate than technology, then you're not going to make much progress. ie, if emulating a human brain is only N times as hard as emulating a flatworm, Moore's Law might do the trick. But if emulating a human brain is more like (flatworm complexity)^(number of cells in human brain - number of cells in flatworm brain) then Moore's Law is unlikely to help for a very long time indeed.