The complexity of clarifying the issue of why is the language endangered must be brought forth objectively. In socio-historical context it can be certainly agreed upon by leading scholars that dominant cultures, whether intentional or unintentional, possess economic, psychological, religious, and social control over those whom they colonised or physically influenced. Where by intention, such as Ad victorem or Quid Pro Quo, macro-cultures of world exert their economic, militaristic, religious, and social power as a means of addressing their ideologies over lesser and ordinary micro-cultures. In unintentional aspects, the degree from which these macro-cultures obtain such influence through the idea that function follows form. In other words, language influence of these larger groups like early Christian missions, whose main purpose was to teach religion were using Spanish as their mode of instruction not knowing that such influence caused the micro-culture for which they controlled to eventually only use their language at home and not in other social settings.
Commonly, the factors that led to endangerment of ones language, especially that of micro-cultures such as Mocovi, is dynamically related by social and cultural disruption of ones environment. One main factor is the loss of structural complexity as ones language is being used for fewer and fewer domains of life. Hence, in social and communicative functions, like daily activities and special ceremonies, where such micro-cultures do not utilise or pass on the language to their children often see a diminished use of their language. Continual non-use of the nature of such common functions in ones culture will eventually lead to the demise of the language.
resource: http://www.ethnologue.com/languge/moc