Because a lot of people employed as engineers can’t build classifiers. They’re able to glue libraries and tools together, build UIs, and write APIs, but don’t have the curiosity or creative problem solving to learn and master a new domain. Even when “master” is scoped to something like this.

On top, most EMs wouldn’t take a risk on an exploration of something “unknown” (to them) and couldn’t get buy-in from a PM.

I say this as an EM. Interview hundreds of people and, while, yes, some people don’t interview well, you might be shocked at the level of creative thinking. Even when “creative” is narrowly scoped to “this is a solved problem in a related domain.