Your post consists of a broad question and an unsupported assertion or definition:
Humanitarianism – that is, the political, economic and military interference in the domestic affairs of a state justified by a nascent transnational morality – is one of the defining and most controversial features of the post-Cold War period.
I prefer the Wikipedia definition of the term: “Humanitarianism is a moral of kindness, benevolence, and sympathy extended to all human beings. Humanitarianism has been an evolving concept historically but universality is a common theme in its evolution.”
In its simplest form, humanitarianism is practiced on a “retail” level: person to person, small group to person or small group to small group. As you have defined it to be “political, economic and military interference”, it seems to be more governmental in nature – in other words “as practiced by a government”. Most governments do not operate in the main in “humanitarian” mode. (Perhaps after large scale catastrophes such as tsunamis, earthquakes, major storms and war damage, but that is specific aid – almost never “military interference” – directed to the victims of the particular event. But even that mode of operation is short-lived; it’s not a Standard Operating Procedure.)
When governments seem to be acting from “humanitarian” modes over long periods of time, then there is usually an ulterior motive. For example, the recent massive influx of “refugees” into Europe from the Middle East and Africa, while it seems to be humanitarian in nature (“helping refugees”), it also has the political and economic benefits to Europe of helping to hide the declining birth rates there that eventually threaten the economies of the European nations in decades to come. Europe does need more people to shore up its population, and this is a way to get a lot of new people, mostly young and of child-bearing age, who could, if they would assimilate and adapt, add to the economies there – and provide some kind of public relations bonus points to the leaders of the nations who act on these “humanitarian principles”. It looks like the idea is blowing up in their faces, but since the Germans had earlier experience allowing a large influx of mostly Turkish immigrants, it might have seemed like a good idea at the time.
In answer, then, one of the problems of humanitarianism is attempting to perform acts that “appear to be” humanitarian in nature while accomplishing something quite different. And “humanitarianism as government policy” almost never works for very long.