why do some people say the set angles are sometimes disadvantages if you can just simply tilt the knife to get a different angle?
The advantage of the sharpmaker is consistency. As long as you keep the blade vertical, you will hit the stones at the same angle. If you start tilting the blade away from the vertical you have to keep the same angle to the stones on both sides of the blade. That means twisting your wrist differently to sharpen each edge.
At that point the sharpmaker has no advantage. You might as well be hand sharpening on a bench stone. You still have to gauge the angle by hand, and you have more surface area on which to work your knife.
