You're correct that materialist analysis has to be grounded in conditions as they concretely and actually exist, sure.

But when the stick is bent too far in the other direction, you get this basically anti-Marxist meme of "criticism from the outside," as if the world working class is not an international class within a global capitalist system. The idea that "western" socialists are somehow outside of the international working class is itself a rejection of proletarian internationalism, which is a bedrock principle of Marxism.

"The emancipation of labor is neither a local nor a national, but a social problem, embracing all countries in which modern society exists"

"The Communists are further reproached with desiring to abolish countries and nationality. The working men have no country."

"The Communists are distinguished from the other working-class parties by this only: 1. In the national struggles of the proletarians of the different countries, they point out and bring to the front the common interests of the entire proletariat, independently of all nationality "