They could alter the animation such that feet don't slide across the ground and keep responsive movement. The result would be a worse quality animation, because the movement of the legs would not appear to be pushing the rest of the body around. Instead, it would look more like the feet are following the rest of the body retroactively, while holding onto the ground.

A good example of this is Factorio's spidertron. When the spidertron moves, the legs follow with a walking motion that perfectly tracks the ground below. In this case, it's a great-looking tradeoff, probably because there are so many legs, and not much animation done to the body itself.