They may let you cheat (just like SparkNotes I guess), but these tools also let people like me who haven't had advanced calculus survive when we otherwise wouldn't. If you pay for the WA service (I don't remember what it's called), you can type complex math in and it will break down how to solve it out. This was invaluable to me in some CS classes where I knew how to implement the algorithms once the math had been detangled, but the mathematical notation was so opaque to me at the time that I would've had no hope of figuring it out.

Obviously, I learned a lot from having it broken down like that so I wouldn't be as dependent on the tool now, but at the time, it was a huge learning aid.