The article puts it this way in a bullet point toward the top:
> DC motors and appliances have higher efficiency and power to size characteristics.
Fast charging is done with DC. Level 1 and level 2 charging uses 110 or 220 volt AC and is quite slow by modern standards.
The reason Level 2 charging is current-limited by your car -- even if you had a very high-current AC source available -- is that to take advantage of a high-current AC source your car would have to carry around a bigger, heavier rectifier. Which would decrease your EV's efficiency just by virtue of being big and heavy.
I believe you meant DC fast charging, unless you were referring to level 2 charging.
In terms of reliability, the inverter is still an extra part that can fail, but on the other hand, it's also much less likely to blow a fuse when your motor shaft stalls on startup.
They do need controllers that use AC, so I don't think that existing devices would work on DC.
Now if you want the ability to adjust frequency and voltage, at large power levels, you're talking about changing the parameters of an inverter. So what it's going to do with AC input voltage is AC -> DC -> AC* (* with different frequency and voltage, synchronized to the rotation angle changes of the drum of your washing machine). This comes with a second advantage: it's easier (and cheaper) to be tolerant to frequency and voltage changes in the wall plug, maybe even tolerant enough to have one device that works in US and EU (and ...)
You're doing this because the power plant is not going to change frequency or voltage based on how fast your washing machine is turning, but doing that makes the washing machine much more efficient.
