Everywhere else, there is only DS, and it involves everything.
To answer your first question though, the training and testing of these models is fun because it feels like a puzzle game: did all my understanding and preparation of the data (and the business) pay off and the model does its job as expected? Is there something I’m missing? What’s the simplest model + configuration I can use that produces acceptable results and what does that say about the problem space? Can I combine models in some way to get the results? Is nothing working because it’s an ultimately fruitless exercise and our hypothesis is wrong? Or is there something we’re missing that is in turn the reason the model is missing something? Etc etc.
Then as the output you get something that ingests some data and then makes a decision with it! That’s cool to me.