The MPPT technique is improving the efficiency of the solar cell. For solar cells you need the sun, which is in some countries somewhat hidden by clouds. Nothing to do about that. MPPT finds the voltage giving the best power performance under all these varying circumstances.
With a knitted MPPT graph:
What is surprising though is that you can make a difference of around 30% in power (on a geographical latitude of 52 degrees), just by looking for the right vertical angle to the sunlight. As you can see in these plots, there are two lines of red dots, representing the power, both lines (red dots) are for the same cell, the only difference is that the lower line is for a cell lying horizontally and the higher line for the angle which gives maximum energy.
This is of course the same for the maximum horizontal angle.
So tracking the sun in both horizontal and vertical direction is as important as the MPP Tracking. This positional tracking of the Sun is a mechanical process, with wear and tear, and costing energy…maybe it is therefore not often used (?).
This observation has also conseqeunces for using solar cells in clothing…whichever place on the garment of a human being will be out of this most efficient direction to the sun most of the time. This means that the efficiency of generating energy with solar cells, just by this fact will be far below the specs of the component in an average timespan.