They are not expelling extremists based on extremism. They are expelling extremists based on public fallout. The remaining ones are effectively their spokespeople.
Germany has a wide range of political parties that cover the entire political spectrum. A party of extremists is not needed for a strong opposition. What German politics needs is momentum, and the will to actually get stuff done, even if it'll be unpopular. The fact that the AfD managed to use and abuse that mindset to gain popularity does not make them the right ones to make a positive impact. In fact, even putting their extremism aside, their contrarian and anti-progressive "everything new is woke" mentality is the exact opposite of what the country needs, for all I care.
I've answered your last question in a sibling comment to yours.[1]
Germany has a wide range of political parties that cover the entire political spectrum. A party of extremists is not needed for a strong opposition. What German politics needs is momentum, and the will to actually get stuff done, even if it'll be unpopular. The fact that the AfD managed to use and abuse that mindset to gain popularity does not make them the right ones to make a positive impact. In fact, even putting their extremism aside, their contrarian and anti-progressive "everything new is woke" mentality is the exact opposite of what the country needs, for all I care.
I've answered your last question in a sibling comment to yours.[1]
[1] https://news.ycombinator.com/item?id=43869432