I don't think this is about giving poor people a regular income, more like a one-time cash transfer. The idea is that money is a good "fishing pole".
In the "fishing pole" analogy: You may give them a fishing pole in the best "central planning" fashion, but they may have little use for a fishing pole because there's practically no fish in the region.
By giving them money, you trust them to decide for themselves whether a fishing pole would be more useful than say a plow.
I think there is a point where people stop trying to be self-sufficient and start relying on handouts. It would be interesting to know what triggers it.
But the assumption that some external provider of aid always knows which kind of aid is better is probably a fallacy.