“The Pharisees thought they’d purify Israel through dietary laws and religious customs. “
Really? I thought the Torah did that.
Rabbinic tradition evolved that was intended as “helper” law, regulatory “guidelines,” for a modern parallel, that would help the Torah compliant avoid accidental disobedience to direct Torah commands. This body of additional tradition was codified as Mishnah, and included such things as ritual handwashing, the Corban Rule mentioned in the article, and an amazing set of Sabbath rules.
IIRC, one such rule involved a rope of a specific length, with a stone tied to each end. With this rope, you could know how far you walked, and thus avoid walking too far. But of course you could always have a servant move the far stone to your next destination, and since a stone is a place, you could “honestly” say you had only travelled thus far between two places. No small wonder Jesus was bent on setting his people free from such nonsense.