Children will come up with their own methods for managing mathematics, the methods that work for them. It seems that Common Core attempts to teach them methods directly, instead of teaching them to simply add and subtract and letting them come up with their own methods. That can't work, since the methods a child settles on are not likely to be the same as those taught in Common Core--and Common Core is bypassing the essential skill anyway, which is to perform the number operations in whatever way that works. 5x7=35, no matter how my brain ends up processing it.
I don’t think they really care whether a child can get the answer on their own or not. It is not conformance. Left to their own devices upon encountering a child with synesthesia, they would fail her/him because the child failed to get to the answer ‘their’ way(s).