Actually it is, especially when you're working with a team of developers. Imagine that your designer puts together a design system built on a soft grid. The ru

Actually it is, especially when you're working with a team of developers. Imagine that your designer puts together a design system built on a soft grid. The rules in the design system are what ensure consistency across the site. If you have a team of developers, sooner or later you'll manage a junior dev who interprets the design as a pixel perfect layout, and starts defining widths on elements per their own personal interpretation. Maybe they eyeball it, maybe they measure it, maybe they measure it but don't include the border. You can catch such things through training and code review, but it puts the burden of managing design consistency on a senior engineer. Starting out with a constrained system is one easy way to ensure consistency of design across large projects.