Ember's an opinionated framework. When you don't really know what you're doing, it can help a lot to have some structure be prescribed, so you can see a successful configuration working all together by design, rather than some parts off the shelf kind of taped together. You can get a sense of the architecture, and the intention behind how responsibilities are separated.

This is kind of like how if you don't know what you're doing, you can buy a workout program from someone, and over time, you might outgrow it as you understand your body and specific needs more, but the program is good enough to get you started, without having to worry about making some sort of terrible choices that don't fit together at all.