I also faced this problem while working in a team of 4 — 5 designers at Lazada (big ecommerce platform in SEA). We also tried to create design library and design guidelines. And force design team member to use the system to keep consistency in design. But I think every company has its own problems.
At Lazada PM and QA want to have perfect pixels mockup, PMs want to see the real prototype on phone, QA want to exactly see how the mockup compared to the demo test build.
Another thing to consider is about the scaling of this design system. I am sure that there will be time design team receives design brief that requires creativity or in other words, exception from the design system. So it needs to have scaling possibility.
It's strange that I have just read another article on medium about “design doesn't scale". So to me at this point I think creating design system and maintain it is the hardest work for design head or team lead, and also depends on the company’s working process. Adapt and create a suitable system.
Just some sharing when I found your article