A German ISP changed their DNS to block my website

"We need more government action and control to protect you from le bad people" does not in fact strike me as the opposite of what happened in Nazi Germany.

Yet, free speech and democracy was exploited by a group that aimed at dismantling free speech and democracy (among many other things)

It's what kept the Nazis from rising again in Germany for 80 years.

So, to prevent that from happening, we ought to dismantle free speech and democracy?

Guy goes to the psychiatrist, he keeps clapping his hands. Explains that this is to keep away the elephants. Doctor goes "But there aren't any elephants around?" Guy replies "See? It's working!"

(I'm sure there's a more sophisticated way to refer to this fallacy, but my point stands.)

Only if you think in absolute ones and zeros

You can prevent organizations whose aim is to destroy democracy by exercising some restrictions on democracy without completely dismantling free speech and democracy.

just as for example you may jail someone and completely restrict their freedom in order to protect others, without completely dismantling democracy

Not only most of europe was overtaken by fascism in the thirties, currently you have democracies that were taken over by authoritarians such as Russia, Turkey and Venezuela.

So it appears to me there are still elephants around

Except in this case everyone is being jailed, to keep them safe from the criminal.

So if Russia, Turkey and Venezuela had stronger governments, they wouldn't be authoritarian?

Yes, if by stronger governments you mean stronger democratic institutions that could have fought populism, that would have helped.

Democratic countries that are corrupt, weak and have poor cultural defense mechanisms against populism fail. In Germany such a mechanism is the one discussed in this thread, in the US it's a strong , almost religious belief in the constitution

Contrariwise, there was a widespread belief that we were at significant risk of cascading computer failures that could take out critical infrastructure when the year rolled over from 1999 to 2000. When midnight struck on January 1, 2000, nothing much happened, and skeptics said "See? It was no big deal. Turns out there was nothing to worry about after all." But actually, software engineers had been working since years before to update those critical systems since years before and their efforts paid off, making Y2K seem like a non-event.

Maybe we haven't observed Nazism rise again in Germany because the policies against Nazi expression, first implemented by the Allied occupying forces immediately after WWII, worked so well.