Exactly. No group has ever won rights by asking nicely. The truth is that it doesn't actually take too large a portion of a population, acting together, to cause a society to come screeching to a halt. Law, order, and the right to private property can only be maintained if the vast, vast majority of the populace is willing to peacefully go along with the status quo. If tomorrow 10% of the population wakes up crazy and decides to just start setting everything they can on fire, we'll be back in the Stone Age within a month. Most meaningful reform has come down to forcing those with power to choose between modest, but potentially painful reform on one hand and "watch as we burn it all down" on the other.

The black population would not have been able to credibly win against the white population if an all-out eliminationist race war had been sparked in 1950s America. But ultimately, they didn't have to be able to win such a war to create a credible threat of intolerable violence. The black population alone couldn't win a total war against the white population, but any kind of wide-scale race war would have completely collapsed the American economy and society. And such a war likely would have had factions receiving military support from US adversaries such as the Soviet Union. The threat of the Black Panthers was essentially, "we may not be able to win an all out war against our oppressors, but if push comes to shove, we can turn the US into another Vietnam." Compared to that potential nightmare, the modest and quite understandable reforms that MLK demanded seemed quite reasonable.

Same thing with workers' rights. "Give us an 8 hour workday" seemed extreme in isolation. But if the choice was, "give us an 8 hour workday, or we burn this factory to ashes" or "give us the right to unionize, or we can start listening to those literal Communists over there promising to bring out the guillotines..." well suddenly an 8 hour workday or a right to unionize doesn't seem so extreme.

It is very much a good cop bad cop dynamic. It's no coincidence that unionization, workers rights, and redistributive economic programs peaked when the Soviet Union was at the height of its power. Literal Communism is a philosophy that can appeal to downtrodden groups anywhere. And when the Soviet Union was ascendant and actively fomenting socialist revolutions and violent uprisings across the globe, they were able to serve as the "bad cop" that allowed modest reformers in the US to be the "good cop" pushing for various reforms and social programs.