Required multiple wars for that to happen, including the American Revolutionary War, and the War of 1812.
Required the American Civil War to abolish slavery politically, numerous violent and non-violent clashes with government forces, piles of legislation and activism. The fight against the attitudes that would like to re-establish slavery is still ongoing to this day.
Required numerous wars in and outside of the US and still has not been fully accomplished. The US is still an imperialist power which directly or indirectly contributes to the oppression of minorities both domestically and worldwide.
Required a world war and millions of deaths to achieve. Their followers still exist and work to re-establish Nazi worldviews and regimes to this day.
Required decades of the Cold War, propaganda efforts, and economic warfare. There are still oppressive communist regimes in the world, and those seeking to establish such regimes in the US to this day.
See the above comments on Slavery. This is still an ongoing problem in the US, from Jim Crow, to the Civil Rights era, and continuing today. Attempting to end Segregation has required piles of legislation, and often violent force to enforce that legislation and prevent segregationist efforts. Efforts which are still taking place in much of the country, and still involve violent force.
None of the problems you listed were "seen off" by "free speech". In each and every case it has been violent force, or the threat of it, often combined with enacting legislation backed with violent force, to address the problem. Which means that if you're insisting on treating edgelord propaganda the same as all of those other problems were treated, then anti-hate-speech legislation, prosecution, and forceful imprisonment would be proportionally justified. Yet you seem to think that proportionate equivalents to the tactics used to resolve or attempt to resolve those other problems don't apply in this specific case. Why is that, I wonder...