Often called the first "meta-genre" which was more about "attitude" than a specific style or sound. Grunge was a response to Punk, which was seen as too insular/exclusive, and which clearly had a limited ability to produce the political change it claimed to stand for.
Grunge, in this context, eschewed elitism by "making pop better", rather than dismissing it entirely. Zach De La Rocha of Rage Against The Machine said the point was to "reach as many people as possible," and that there is nothing inherently wrong with what Punk would call "selling out."
One can elaborate this position to say that a hatred of so-called "sell-outs" necessarily distracts from broader, systemic issues by narrowly focusing on individual artists or bands which are not "authentic" enough for Punk.
While many Grunge bands were not as overtly political as Rage or SOAD (many would say they aren't even Grunge), we can interpret the lack of explicit political message as in itself a statement.
One could say it is a statement of Nihilism or privileged ignorance, but one could also interpret it as a statement that perhaps Art is just not the place for political struggle...
This statement should ring somewhat true, considering the failures of Punk, of Hippies, of Goths and Scene kids to really make any meaningful impact on politics.
As one anonymous curmudgeon quiped: "Punk is CIA" One could argue that the incorporation of radical politics into sub-cultures is a method of "capturing" radical energy and allowing to be expressed in the form of art and music, rather than political struggle and organizing.
Furthermore, with the perverse financial incentives of the entertainment industry, artists are rewarded for expressing radical political sloganeering far more than they are for actually participating in struggle.
This is all a possible interpretation of Grunge, of subcultures and their relation to politics.