In my experience, following the advice given in the second paragraph is a good way to end up with both unmaintainable software and unhappy users. Having a desi

In my experience, following the advice given in the second paragraph is a good way to end up with both unmaintainable software and unhappy users. Having a design system upfront encourages consistency in visual and interaction design, and tends to nudge towards a consistent implementation. Consistent implementation is usually easier to iterate on, and tends to remain consistent with lower effort in the face of changing requirements. I've used products and worked on projects that were built using the "pure" iterative approach they're espousing. You can always tell, and it's never been positive.