hate groups were quieted to the best of our ability, slowly erasing those archaic viewpoints
We absolutely tried that. The approach failed quickly and spectacularly in the past 15ish years, and even backfired. Frankly, whether you call it shunning, cancel culture, or people exercising their rights of association, it’s not very effective in the Information Age.
I’ve personally pivoted to the much more exhausting, dogged method of dealing with them fairly, and simply taking the time to explain where and how they went wrong. This is very time consuming, but can work sometimes.