Again, there are no capacitors car side to be produceing thermal load in the first place during dc fast charging in the first place, and that thermal load is not the primary barrier to how much current can go into the battery without degradation anyway. After all, if it was we would just upscale the cars heat pump and be charged in five minutes.

Car charging is not coordinated to the point where they all plug in within a few seconds, and if it was a few second randomizer on when eqch timer actually starts charging would accomplish the exact same effect without hundreds of millions to billions of dollars in new grid scale capacitors and inverters.

This is also unlikely to become a significant problem because a lot of the grid is moving to battery backed solar and wind, where the limit is price per megawatt hour and as such said batteries can provide far more current than the grid could consume. You might be limited by inverter capacity, but storage capacitors are also fundamentally a DC technology so you would need them anyway.

This may turn out to have benefits for electronics that rely on already specialized supercapacitors, but it can by definition not have any impact on processes that are not currently limited in any way by capacitor technology like battery bulk charge current, the thing that actually limits how fast a car can fast charge.