There’s no grey area in what you’re saying and it’s a problem. Designers evolve and this advice cannot apply to any stage in a designers evolution. It’s imperative to first learn to design pixel perfect and then to learn about business. Designers should focus on design, then learn to code (at least at a basic level, at least to establish that useful mindset) all the while trying to understand business principles when they are faced with projects with a big impact. Designers are by nature opinionated and oriented toward problem solving approaches. And this also means a curiosity for the business side of things. Those who aren’t will be bad at both.