Despite being based on science, software development is full of bs, opinions and lacks measurable metrics. How "clean" this code is? In numbers between 0 and 1 for example. What's the metric there? Does using polymorphism automatically make your code clean? We cannot reliably reason about even single responsibility b/c there's no real measure how to count responsibilities of a function. In such la-la-land some desperately seek any formal measure, and there's one - performance - you can actually put a number on a piece of code. But you cannot do this for code "cleanliness". So some people prefer to ignore unmensurable trait and replace it with measurable