Earlier quoted context omitted.
To both of your points: the beer hall demagogue wouldn't have gotten to Chancellor if the German elites hadn't decided that he really couldn't do that much damage and we may as well let him be chancellor to quiet down his followers. Even after the putsch, he got a very light sentence because the judge was sympathetic with his right-wing cause. You're both right to some extent. A huge amount of damage was done by one…
All events have multiple causes. But history turned on what he did, and would have been very different otherwise.
Obviously, calling out for violence and building organizations that commit atrocious acts of violence is a bad thing.
However, it is really hard to do without the help of others.
If you start arguing that your country should invade your neighbors and mass murder various types of people, the people listening have a choice in how they react - do they politely remind you that we're generally happier and richer if we're nice to each other and "treat others like we'd like others to treat us", or shout "JAWOHL MEIN FURHER" and go invade neighbors and mass murdering undesirables?
The problem isn't always the guy shouting hate, it's the crowd listening and implementing hate.