Those kind of things used to be a lose lose proposition back at the time of haml (?) and all the yaml like templating languages. That was more than 10 years ago. The reason was that any designer that could actually do html was able to write an erb page, maybe except loops and logic, but they could understand them if a developer added them into the page later. On the other side with one of those languages, and more with phlex, only a developer could write the views so we were back to the 90s with photoshop layouts.

Furthermore your can't copy and paste examples. Think about Bootstrap components. You have to really write everything from scratch.