Morningstar MPPT Controller's Maximum Input Power Rating

I'd guess that they just vary the switching on/off time with no extra heating concerns. After all the electronics provides more voltage/amps when the batteries need it and less as they become charged.

This is the first instance that I'm aware of where a mfg has written information on the benefits of a larger array than the stated limit.

Also if you consider a home/industry tracked array (physically following the sun) the controller could easily be at or beyond the maximum array input for many hours per day.