HN has been having lots of discussion about racism, just as the rest of society has been (or rather, societies, since many countries are represented here). If your question ("Is HN a place where discussion about social problems [is] not allowed") comes up, that can only be because of unfamiliarity with the history. If you want to get more familiar, HN Search is a great resource (see the box at the bottom of every page).
HN has been having lots of discussion about racism, just as the rest of society has been (or rather, societies, since many countries are represented here). If your question ("Is HN a place where discussion about social problems [is] not allowed") comes up, that can only be because of unfamiliarity with the history. If you want to get more familiar, HN Search is a great resource (see the box at the bottom of every page).
The process of how we moderate political and ideological topics on HN is pretty stable by now. If you want to know what it is, check out the past explanations at https://hn.algolia.com/?dateRange=all&page=0&prefix=false&so.... There's a lot there; you could start with https://hackernews.hn/item?id=21607844 and https://hackernews.hn/item?id=22902490.
People often feel like their most-important topic is under-represented or outright suppressed on HN. Even the most common topic feels "censored" to some people (see e.g. https://hackernews.hn/item?id=23624962). This is an unfortunate consequence of frontpage space being the scarcest resource on HN: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que....