Which they could have easily solved by not making rapier a 1d8 weapon, or by making it Special Versatile weapon that deals 1d8 if wielded alone and 1d6 if wielded with an off-hand weapon or shield.
The problem remains that common use dual wielding (big weapon plus off-hand weapon) such as rapier/long sword + dagger or mace + hand axe are still tied behind the same feat that enables ridonkilus big weapon dual wielding despite being thematically very different.
