You still need rich parents, because you're not allowed to work much to support yourself.
You do however need to show you have EUR 8,640 before you get the student visa [2]. Very poor families would not be able to borrow this amount, so it acts as a barrier for them.
[0] https://www.daad.de/deutschland/in-deutschland/arbeit/en/914...
[1] https://www.google.com.au/publicdata/explore?ds=ml9s8a132hlg...
[2] https://www.daad.de/deutschland/nach-deutschland/bewerbung/e...
They can also work more than 20h/week, loose their student-status and still study.