This all sounds to me like DG's definition of 'bullshit'. David Graeber is an anthropologist, ie, he takes a wide view of humanity: many societies, including societies not that alien to us, manage to function without this kind of work. Why is it suddenly indispensable? It is not a business advice book about running an individual institution, it is a wider social critique about how we have set up our society and economy.
> let him spend a year managing a mid-size organization, say 60-80 employees,
Graeber is an anarchist anthropologist and would critique the idea of a top-down capitalist firm itself (ie, the deeper question: why do we insist on structuring labor this way?). He is not telling anyone the best way to run it.