Sounds like a system which could easily be abused. "politeness" and "decency" are ripe for all manner of interpretations.
In the US we see that the only things keeping authoritarianism at bay is larger the people following norms (like the peaceful transfer of power after losing an election), and the executive obeying orders from the judiciary. All it takes is for a group to not to that any more and boom.
Short road to where 'slander' means any criticism (however objectively true and justified) of people in power and you get a swat team at your door and steel boot on your neck.
>Sounds like a system which could easily be abused.
It is constantly abused, the issue is Germans have gaslit themselves into thinking that it's the right thing to do "because nazism was bad", so they have Nazi levels of speech censorship to fight imaginary Nazism, because once you label someone who disagrees with you as a Nazi you are free to censor them, which then in turn is causing the uprising of actual Nazism because people are tired of being censored for having opinions that oppose the mainstream narrative. Germans are really a difficult bunch to reason with logically.
The US is in no position to tell anyone about how to avoid authoritarianism.