It's not the fact that peoples attacks are physically going through their blocks, it's just that there is a bug with this game that on your screen it shows the correct block and on the person who's attacking you screen, it shows an incorrect block. Don't know why it's like this but that is the reason the "attack going through my blocks" myth is out there.
Because when i duel some people that are in my clan, they say i went through their block, although on my screen they had an incorrect block.