like 1 out of 40 players uses a crushthrough weapon, easy to avoid.
As said, its much harder than you think, you are basically chancess against any other solid 2hander or polearmer, upswings are extremy slow and can be canceled anyway, as already mentioned, by a simple nudge.
Also, it requires more than 24 Str to crush trough something, which automatically gives you a lack of agility