It harms nobody. It just offends a lot of people.

So, right after the holocaust, most European countries made it a crime to advocate Nazi ideology. At the time, the continent was unstable from the aftermath of the 2 largest wars of all time and the last thing they needed was to deal with Nazi sympathizers causing problems while they tried to rebuild their communities and economies.

At the time, it was totally reasonable to ban people from being Nazis. Just lock them up so they cause any more problems than they already have (meaning the holocaust).

Since that time, there has been no really good reason to remove the bans. I mean, if any otherwise normal politician tried to remove the ban, then they'd be branded a Nazi sympathizer and their career would be over, so I doubt anyone wants to touch that subject.

To be fair, the only people who are negatively affected by this are actual Nazi sympathizers (nobody cares about them) and people like this guy who are making jokes. It's disappointing from a free speech point-of-view, so maybe there should be a concession for jokes? Still, I doubt that would ever happen.