It's not only Germany but also Austria and France (until 2004?). The Germany Wegzugsbesteuerung is meant to prevent cases where Germans leave the country for more than seven (or twelve upon request) years, e.g. to Switzerland, sell their Germany company stock and profit from paying a much lower tax or none like in Switzerland. Steuerflucht, tax evasion is prevented with this and there are certainly many who'd other move abroad, sell without taxation and move back again. There a plenty of exceptions though with countries Germany has a Doppelbesteuerungsabkommen (double taxation treaty) with to prevent cases where the individual would have to pay taxes in both countries.

Personally I never heard of this tax before, despite being a German living in Austria, but then: The tax targets wealthy individuals with company holdings trying to evade taxation. https://de.wikipedia.org/wiki/Wegzugsbesteuerung

It is a bit different though, because the German exit tax applies to companies and people holding more than a 1% share in a company. So no exit tax if you hold bitcoins as part of your private assets...

Agreed that there is some tension with EU principles, but it is difficult to get it right. Building a company in country A for 20 years, then moving to country B for 184 days to sell it completely without paying taxes also does not seem like a fair system.