@ddsgad yes you’re right, most of this guide is extremely out-of-date. I’ve been working on general docs improvements recently, and hope to get this one updates/replaced in the next few weeks.
As you’ve mentioned, real-world examples like DiscoTOC can be a good reference. And then here are some specific guides which are more up-to-date:
For general information about Ember and its components, I recommend looking at the Ember guides.