I think this is a simplification (to the best of my knowledge). It isn't a myth, instead it has exceptions for reasons. It isn't a joke either - German football supported it strongly when it was last tested.
Wolfsburg and Leverkusen are outliers because they were what they are before the 50+1 rule was brought in - exceptions due to longstanding past funding when rules were brought in, as they are works teams rather than the more common community/municipality club. They are therefore stronger examples of why forced 50+1 isn't really a fair option for privately owned clubs.
Leipzig are a construct that adhere to the rules having subverted them completely, and the rest of German football are wildly unimpressed with how it was done.
The 50+1 is only about 20 years old, I think, and arose when private ownership started coming into German football. About 10 years ago, a club (Hamburg, maybe) proposed overturning it, a proposal that was overwhelmingly voted down.