I'm a bit rusty on these things, so bear in mind that I may get some of the details wrong below.
My concern is that the AC input of a typical EV charger is a boost converter, to achieve near-unity power factor. You need a boost converter, because at 20% of peak mains voltage, you need to be drawing 20% of peak mains current, but 20% of peak mains voltage is a lot less than the battery voltage. A boost converter is an inductor and diode in series, with a semiconductor switch between them. The inductor is the component closest to the AC input. There is a diode bridge in there, but it will continue conducting, and can be ignored for the purpose of this discussion.
This means that if you happen to interrupt the charger near the peak of AC current, the inductor is going to want to keep that current going, so your contactor is going to have a hard time switching off that current. In other words, it will tend to arc. The arc will only last till the next zero crossing of the AC current, so it's not catastrophic. However, if the contactor does manage to sever the current abruptly, the inductor will kick up a high voltage in an attempt to keep that current going. That's what inductors do: they have to obey E = L. dI/dt ; E is the EMF (voltage) across the inductor, L is the inductance, and dI/dt is the rate of change of current. If you cut off the AC current instantly, then dI/dt is very large, so E becomes very large, easily several thousand volts. If you've ever played with an inductor and a flashlight battery as a kid, you'll know all about this inductive "kick".
This large and sudden increase of voltage across the inductor could damage the charger. I think that a properly designed charger would have snubber components designed to absorb the inductor's energy safely, which at the same time would prevent the contactor or breaker turning off power to the charger from arcing so much. In cheaper chargers, these may be undersized, so that after a few such interruptions, the snubber components wear out (usually open circuit, meaning that they don't affect the operation of the charger, except that they no longer have their protective effect). Hopefully, in a production EV, they don't skimp on these snubber components.
So I think that this is the gamble you take when frequently interrupting the charger input: you're gambling that the charger designers have included the snubber circuit, and that they paid the extra to size them correctly, and that the repeated absorbing of the inductor's energy doesn't wear them out eventually anyway.
2012 Leaf with new battery May 2019. New to me June 2019.