Is this German beer any good?

[Kongo Otto]

Originally Posted by Julhelm

Not true. It is the supermarkets who are not allowed to sell alcohol over 3.5%. You can in fact buy proper beer like everwhere else but you have to go to one of the state alcohol stores - 'Systembolaget'. They tend to stock a pretty decent selection of lagers, weissbiers, and microbrews.

That's a system i don't understand at all.
Why must i go in a Liquor Store in the US or a Systembolaget in Sweden?
What's the reason for this system?
Here in Germany i go to the local Supermarket and pick my stuff.