Sure! But the method of learning doesn't have to be the method of assessment. In fact, as pointed out upthread, it shouldn't be.
When students are doing homework you want them to form collaborative study groups or freely consult any other source, if it helps them learn. Fear of plagiarism is antithetical to that.
I think a related problem is that many university educators have a pretty abismal understanding of education itself. For some of the, the notion that leaning tools shouldn't necessarily be assesment tools is rather suprising.
