Michael Harner's approach to shamanism was quite in keeping with the scientific method. He looked for the mechanics of the religion: he, like Eliade, was concerned with what they do, the ways in which they alter their consciousness. They were both seeking some universal Essence of Shamanism, something they could put in a test tube, something that would produce verifiable results under controlled conditions. And, to a certain extent, they succeeded.
Take enough Iboga, Ayahuasca, or Peyote and you are almost certain to have what feels like a mystical experience. You can also get some interesting perception-shifts by fasting for several days, dancing in circles for long hours, and engaging in other rigorous and sometimes life-threatening activities. By sorting through reams of data (another Western approach) modern shamans have been able to isolate some of the most effective of these techniques and create ceremonies (i.e. controlled conditions) under which altered states can be replicated.
The problem is that the Neoshaman and the tribal healer are using the same means to very different ends. Tribal shamans are mediators and diplomats. They seek to protect the interests of their clan and its members in a world/s filled with allies, enemies and neutral parties. Many Neoshamans, by contrast, come as colonists and conquistadors. The oilman drills deep into Mother Earth in search of profit: the Neoshaman meditates on Mother Earth in search of wisdom, abundance, prosperity, healing or other polite euphemisms for "personal gain." The interior and exterior worlds are treated not as complex interdependent ecosystems but as resources to be exploited.
It would be easy enough to write this all off as yet another sign of cultural appropriation and the commercialization of the sacred. But there's something deeper here, a way of seeing which is absent in most contemporary Neoshamanism. The shaman is an entity within a living world, a being defined by hir interactions with other sentient beings both human and nonhuman. The Neoshaman lives within a material universe, one which is essentially inert and where sentience is an exclusively human trait - or where, at best, human intelligence is seen as the apex of evolution to date. In such a world, things can only have meaning and value insofar as they are of use to the Neoshaman.
For me, a Shaman is someone who acts as an intercessor and a messenger to the various beings who share the Web of Sentience. Sie communicates with these corporeal and non-corporeal beings and works with them to accomplish certain tasks. Commercialization is not an issue. There are many cultures where spirit-workers are honored professionals and spirit-work a solid career opportunity. What is important is the way in which the Shaman interacts with the worlds of matter and spirit: it is not a way of doing so much as a way of seeing.