If you look at the presentations, they are comparing only 2 or 3 values, so graph itself is meaningless because visual delta between two values does not mean anything.

How so ? One is showing power consumptions in milliamperes, the other is score marks in GFXBench - both of which should be quite meaningful.

Ofcourse you have to know what GFXBench is measuring.

What information is the graph actually showing? That number X increased, sure, but not in any way by how much. By not having a labeled Y-axis, and not having the y-axis start at zero it is basically meaningless from a communication standpoint. It might be effective from a marketing standpoint, but only in the misleading way.