Those first two principles help promote simpler and more stable APIs, which is a must for large projects with many teams. If you iterate on the interface betwee

Those first two principles help promote simpler and more stable APIs, which is a must for large projects with many teams. If you iterate on the interface between large enough layers, it ends up anywhere between "very costly migration" and "breaking change". In a smaller project though, then yeah, it's better to just refactor away one's woes. Like you said, if it's not really needed, they can have their drawbacks.