Emphasis on the "reasonably focused on one domain" part - it's when you're passing through your entire program state in one gigantic state object that things ge

Emphasis on the "reasonably focused on one domain" part - it's when you're passing through your entire program state in one gigantic state object that things get messy. Also, I've been led to believe that design of constrained / embedded systems follow different rules. Your code can be unreadably complex if you have to squeeze out that extra performance (however, even then, it should probably be well-commented or well-documented), and generally (though not alway) such programs will be smaller and made by smaller teams. It's when these kind of practices are applied in enterprise software with large number of programmers, where maintainability is more important than performance, that this is an issue.