First of all, the kid got permission to get a BP next year with their parents' support...

Many people do not recommend BPs as beginner snakes. These recommendations were given to someone who we didn't know at the time would have help/support both financially and in husbandry from their parents. I'm glad you could raise chameleons, snapping turtles, and finicky frogs at the age of 13, because most children that age would not be able to meet the husbandry requirements with no financial help or help getting the husbandry correct.
Also betting you didn't pay for everything yourself; or you were the world's richest 13 year old.

I started with garters at the age of 12 and never had any trouble with them. Yes they can be a little flighty, but they are a lot more forgiving of husbandry issues than a BP.

IMO research is not a substitute for experience. Starting with a tropical species that has to have very specific temp ranges/hot spots/humidity requirements is very different than starting with a temperate species that barely even requires supplemental heat. Someone who isn't used to constantly checking on these parameters could easily get overwhelmed with it or make mistakes, especially a child. Saying that tropical species are not ideal beginner pets is a far cry from logic that would "deem everyone irresponsible".