Hey FReind before you ignite your antisemitism fuse by putting words in my post, take a break and deep breaths.
Torah is written Law given by God. That is what God told Moses the Israelites must follow neither turning to the left nor right. Torah, that's it not Torah and the traditions of Aaron or his sons. We do know when man-made traditions were introduced the Israelites sinned by idolatry, sacrificing in the wrong places, and departed from God's Way His Torah. Jesus upheld Torah not man-made traditions. Period. I offered the reasoning in three posts now.
The Jews today cannot follow Torah fully especially the atonement because they have no temple. You know the history. So if you want to base a Christian theological practice (prayers for the dead) on man-made Jewish traditions Christ condemned have at it.
There are almost two million Torah observant (Orthodox) Jews in the world today that observe the Mourner's Kaddish, your gainsaying of this fact notwithstanding. Jews can follow Torah even when there is no temple made of hands.