Although he's correct at a high level, I'd say this should be handled more like the advice given to programmers on optimization: Optimization for beginners: Do

Although he's correct at a high level, I'd say this should be handled more like the advice given to programmers on optimization: Optimization for beginners: Don't optimize Optimization for experts: Don't optimize - yet. What I've observed, over and over (for the past 20 years of Java development) is that beginning programmers don't really see much point in object-oriented design, and default to static functions (Java's equivalent of "free functions"), but they also end up needing some shared state... so they make the shared state static, too (Java's equivalent of a global variable). Every "enterprise" Java project I've worked on since about 2002 has been "designed" this way: almost all the data is public static (e.g. the "singleton" abomination) so you can't run any of it without running all of it. On the other hand, if developers just defaulted to designing objects even if they don't really get why, they'll end up with a composable, testable system by accident.