I spent 15y+ writing in C/C++/.NET and and I have hard time understanding what is going on with xz with all twists and turns, why you are expecting your brother to understand and NYT will give you clear explanation that laymen can understand this very intricate hack ?
The issue isn't about explaining xz, it's about explaining Postgres. "It's a very popular piece of database software, and Andres' job is making sure that whenever people make changes to it, it doesn't get slower". There you go.
