The GADDAG is a standard datastructure - the original paper, linked from the article, is from 1994. The article doesn't pretend to invent the GADDAG, nor claim

The GADDAG is a standard datastructure - the original paper, linked from the article, is from 1994. The article doesn't pretend to invent the GADDAG, nor claim to compress it better than others, only to try and explain how to simplify and pack a GADDAG. The steps would work on all DAGs generally. This is nothing new, but hopefully its new to some of us and a nice article.