I wrote this article, and appreciate your framing here. A few things contributed to this effect that I think are a bit clearer with hindsight. Central to this was a lack of clarity between designers and engineers about what the state of things actually was. Designers assumed that engineers had been doing some of this work in building shared components, while engineers trusted that designers were aligning with each other. A lot of that happened organically when we were smaller but as we grew faster, those assumptions start to break. Eventually, we were far along before recognizing how much some of our patterns had diverged.

We had a pretty good idea what needed to happen to fix it, but there was a ton of work happening to maintain our same quality at scale across all of our feature teams. When you're focused on maintaining and building toward better reliability, it's harder to slow down and centralize principles, components, etc.

In the end, it's difficult to get people to agree to one thing, much more so when you're adding more and more people to the mix. We're in a much better place now. More than just having an interface library, we've created a framework for debating the various parts of the system and reinforcing that understanding that was missing early on.