How many firings for presumed inflammatory conduct have you witnessed or hear from first-hand witnesses? Personally, I've been fortunate not to have experienced any of these, but I do believe they exist and reading about them is useful for informing my worldview. It's helpful to understand how corporations and institutions are ingesting and digesting societal trends around evolving cultural awareness of injustice in order to protect their commercial interests.
Very serious injustices have occurred within the recent past. Take, for example the 1985 MOVE Bombing, in which Philadelphia police bombed a house in a predominantly black neighborhood during an armed standoff with the MOVE group. Whether or not you feel the bombing of an armed group was a justified use of force by police, the subsequent 61 homes that were allowed to burn down are harder to justify. This was followed by the ethically fraught decision by the Philadelphia Health Commissioner to cremate/dispose of any human remains without contacting family members, with the ultimate result that those remains were used in UPenn and Princeton "forensic anthropology" courses without any chance for their families to reclaim their remains.
More recently, I personally witnessed Philadelphia police corral Black Lives Matter protesters into an enclosed space on the side of the highway with no exits and fire tear gas into the crowd. On the news, I watched a number of similar confrontations take place in multiple cities in the nation.
When inequality continues, I have come to appreciate that the ability to feel that a grievance is historical is a privilege. A significant motivation for people to turn to history is to better understand the struggles through which they are currently living. For these people, understanding the historical context is not a way to bring up old grievances, it is a lens through which they can properly understand how systematic disparities in due process and access have produced today's injustices. It is an aid to better identify how currently extant systems create unfair conditions at a large scale.