Comment by Arainach

The ability to quickly graph functions and see them visually is an enormous aid to learning. Similarly, for various topics like statistics the ability to operate on a dataset is beneficial. Doing all of the raw arithmetic that goes into Chi Squared or whatever isn't particularly important for statistical analysis, and being able to get to the important bits faster is very beneficial.

Where to draw the line depends on the course. In general tools that "give the answer" for something where thinking provides insight are bad in education - for instance, a CAS which will simply compute derivatives isn't beneficial when taking Calculus. Things that eliminate grunt work not useful to that intuition - like computing the same formula 40 times to draw a graph by hand - are beneficial.