They are a CLOSED debate of nine souls on matters of utmost importance and urgency that affect 280 million citizens, a closed debate society whose decisions typically bind those 280 million citizens not for mere months or even years, but for generations.
By wide-ranging, I mean that the text of their opinions cover a lot of ground. Laymen shouldn't be surprised when opinions include details like this. In law school, I've seen opinions that include quotes from Broadway musicals.
It's all dicta. It is not the relevant part of the decision. SCOTUS Justices are not known for their brevity.
The court ... claims halfheartedly that a national consensus has emerged since our decision in Stanford, because 18 states - or 47 percent of states that permit capital punishment - now have legislation prohibiting the execution of offenders under 18, and because all of four states have adopted such legislation since Stanford. Words have no meaning if the views of less than 50 percent of death penalty states can constitute a national consensus.