Well, whatever the article says, isn't the actual reason "we have this other one we built using SQLite"?
The fundamental difference is: sqlite is a cathedral, git is for bazaars. That's kind of a big deal.
It's not a "passion project" by any means. It's a highly developed, well engineered piece of software and there's lots of other non "passion projects" that would do well to learn from it.
I don't mean to disparage SQLite in any way, it is quite the achievement, but your characterization is mistaken.