The most important distinction between movements like pro suffrage, anti slavery, etc and most modern movements was a well defined win condition. The end of the pro suffrage movement was one law. The end of anti-slavery was more complex but still fundamentally came down a change of law. The end of BLM is...?
In a way modern movements tend to be like modern wars such as 'The War on Drugs' or 'The War on Terror.' These are neverending wars that can never be won, nor lost. And when violence begins to become associated with these movements, then it's infinitely more damning since that means there will also be no end to it and you'll invariably breed a counter-movement, which can lead to a long term divide in society which, again, has no end.
In a way modern movements tend to be like modern wars such as 'The War on Drugs' or 'The War on Terror.' These are neverending wars that can never be won, nor lost. And when violence begins to become associated with these movements, then it's infinitely more damning since that means there will also be no end to it and you'll invariably breed a counter-movement, which can lead to a long term divide in society which, again, has no end.