Federal jurisdiction is 2/3L elective though, but you'd think a justice would be familiar. Modern jurisprudence requires that a case be dispensed with on procedural grounds if such infirmities exist. Substantive questions are only to be addressed after jurisdiction is firm. This perseveres substantive questions for future determination in many cases. Without such a rule, courts would quickly take up and decide substantive questions for political purpose and effectively prohibit the evolution of law over time, which would likely lead to the quick collapse of the legal regime (it's going to collapse either way, but it will last much longer with such a rule in place).