There is alot to what BW says. It quite possibly be some sort of era thing. At certain points in time there where lots of groups in France, UK, Sweden etc but there seems to always have been alot of crew in Germany (or atleast with alot of german members). For every era there has always been atleast one really good German crew while the rest come and goes.
If nothing else success does breed success. One great groups leads to more since people had falling outs or decided to change names etc for various reasons.
WK; Lots of weird people in germany? Do you really have to ask ? 