Hi,
I don't think so.
Either your regulation is input referred (MPPT) with varying output conditions (voltage, current)
Or your regulation is output referred (usually V, sometimes I) but with varying input conditions.
Imagine:
If your load is a light bulb, an audio amplifier, a PC, a refrigerator....all need a fixed voltage...and the current is unknown somehow.
(refrigerator ON/OFF, audio amp volume..). Solar cells with MPPT isn't useful...either there is enough sun energy to power the load or the system will fail.
If the load needs 100W, but there is only 90W available, this will cause a problem.
If the load needs 100W, but there is 150W available...then you don't need MPPT to use the full 150W.
But if you have to charge a battery, then it is completely different.
Klaus