But it’s possible to extract value from it if you have a culture where designers build prototypes, and you can use those prototypes for user testing, feedback, demos and pitches, while the code is being built. But it’s rare that companies have this culture.
I know this is a cliche phrase, but when you're trying to align stakeholders (PM, manager, VP, dev lead) on a product, it is genuinely very useful to have really nice, hi-fi mockups to make sure everyone is talking about exactly the same stuff.
It's also definitely a scale thing. If you have 500 developers, it's probably worth putting in some extra sweat just to make sure they're all using the exact same button, etc
If you have 10 devs... yeah, hard to justify a super-perfectly-polished design system for every single bit of your frontend, IMO.