Gramatically perhaps, but in context these sorts of statements about the personal characteristics of groups of people are generally understood to be generalizations.
"Ravens are black" ==> "All ravens are black"
"Germans like beer" ==> "Germans have a significantly greater tendency to like beer than people in general, though of course there are some non-beer-liking Germans"
It could be an interesting question in linguistics to figure out the difference between the two types of "Xes are Y" sentence.
