I think the point is that frontend engineering is a broad field, and everyone had gaps in their knowledge, especially specialists who focus on specific parts of

I think the point is that frontend engineering is a broad field, and everyone had gaps in their knowledge, especially specialists who focus on specific parts of the stack. It's possible to provide a ton of value on very complex frontends without doing much in the way of CSS, for example. I've been part of projects where the UI layer was handled in a dedicated library, and unless you wanted to be part of that team, you didn't have to understand much more than which React components to use when. Graphics are a specific subfield of frontend that isn't relevant to most apps, and it's possible to go very far without being exposed to these.