Ones and twos of MW are indeed tiny loads, there is a 1MW motor where I work that gets flicked on and off like a light switch, but hyperscale canters are in the >100MW range, that's >1% of even the largest generating stations in the USA.

And you're not aiming for some physical resonant frequency of the entire grid, just the controller on your local generator, getting it to ramp up and down chasing just behind your changing load.

I live in Ontario and in the past week the difference between our highest and lowest demand was ~4.5GW, but those changes take place over hours. If you can ramp up and down a 0.1GW load over minutes there is going to be a point where some control loop can't keep up. Generators have physical inertia but compute loads do not.

I agree that it's not trivial, not cheap, and not efficient but with the state of the world it would not be a surprise if some nation thought it would be useful to burn resources in order to disrupt an important event, maybe elections?