Doesn't the ABS pump the brakes for you? At least that's what i learned in driving school.
Yes it does, but it does it rapidly.
When you're on a slippery surface, with the tires sliding you have to release the brakes if you want to get any steering going on at all, and even then trying to steer too much will get you again out of control.
I'm surprised that the driving training in Canada doesn't include any training on a slippery surface, in Finland there are two long sessions of driving in a training area with curves covered with oiled metal sheets.
Of course, when it's snowing it's just best to take the curves a bit slower. Unless you're driving a military truck on a small road in the woods. even a 13t 6x6 slides quite nicely