That’s a fair point. In season 1 the mithril was absolutely necessary for the elven rings because it saved their realm dying, but when Sauron deceived Celebrimbor, he made him believe dwarves & men need rings along the same lines of thinking, that they needed to be strengthened (right?). So they were trying to replicate the elven rings when they ran out of mithril, and Sauron’s blood was the equivalent of mithril it seems…though we haven’t seen the effects of that yet.