3D Studio Max is not specifically setup for 2D skeletal animation. While one can do it, it's a cumbersome process. Another issue with using 3D Studio Max is that basic features, and more so, advanced features like IK, paths, mesh deforms, etc. may be hard to get running in whatever game engine you are using.
With Spine, you get a solution specifically focused on 2D skeletal animation, plus first class integrations for pretty much every game engine under the sun.
