Whataboutism is bad, but there's a distinction between whataboutism and making comparisons to get a sense of the true scale of the problem. If you're not allowed to ever compare relative scales of things without being accused of whataboutism then we're paving the way to making every molehill a mountain.

Two average American's beef consumption for training GPT-3 would place the cost in water of training GPT-3 at 1/150000000 of the US beef industry's average water consumption. That means it's a rounding error relative to all the other uses we place on water, and pointing that out is not whataboutism, it's putting the problem in its proper scale.