When we use dropout, then I have seen the input to dropout is our output from some layer like Conv2d, or MaxPool2d, and then certain number of elements are zeroed out, but instead of zeroing out these elements in our input tensor, why do we not instead zero out weight elements, indicating that we do not want certain weights to get updated, that is only a few weights would get updated, rest of them would either stay as they were or would be zeroed out, that is something like, drop weights.