The meme doesn't stigmatize mental illness because it's not talking about mental illness.

If anything, pathologizing the predictable and inescapable results of living under oppressive systems designed to keep you as down and alienated as possible as a mental illness, instead of a perfectly valid reaction to living in dystopia deeply and negatively impacts how we treat actual mental illness.

The idea that pointing out that we have societal problems pills can't solve is somehow stigmatising actual mental illness (which pills can help) just goes to show how deeply indoctrinated society is in to toxic individualism.