You can run a 10Kw panel with no load at all, the voltage just goes up to the full rated open circuit voltage.
Just like a battery with nothing connected to it.
As you apply more and more load, the voltage slowly falls, and continues to fall as the load is further increased. Power in the load increases too, just as you would expect.
But at some point, the voltage really takes a dive as more load still is added, and the voltage drops much faster than the current increases. If you measure the actual power in the load, it will have dropped. The panels are now overloaded, and working very inefficiently, a situation that should be avoided.
That is the reason for adding a circuit that prevents overloading the panels, and only permits the panel voltage to be drawn down to the maximum power point (MPP), and no lower.
Under a really dull grey sky, with total cloud cover, your 10Kw panel may only be able to produce 500 watts, so the MPP circuit only allows you to get those 500 watts and not overload the panel any further than that.
When the sun again shines, the available power increases, and the MPP circuit allows whatever power is available to be drawn from the panels which may be anything from zero (at night) to the full 10Kw in perfect conditions.