Because the argument they're making (which is valid, but I don't agree with it) is that lumping all of non-Western humanity under such a homogenous label still

Because the argument they're making (which is valid, but I don't agree with it) is that lumping all of non-Western humanity under such a homogenous label still gives "Western" (i.e. Eurocentric) philosophy an undue weighting. The implicit assumption I disagree with is that this constitutes disproportionate representation due to the population size covered or even culture and breadth of ideas - regardless of how complex or relevant the literature is to whatever unstated agendas there are.