Sorry - omits is the wrong word, because of course Phoenix uses that stuff. More that in my experience, for the kind of "in the framework" developer that I've run into in the Rails space, the mapping to using Phoenix is very simple and doesn't demand of the end user the conscious use of processes, genservers, etc. -- it can, and from POV often seems to be used as, plug-and-chug. This totally isn't a criticism either, I want to stress; it's the mark of a good framework, that you don't necessarily have to care about that stuff to ship a thing.

At my current company, we use Phoenix and we use a lot of its bells and whistles. But we also have a lot of people who understand OTP--definitely way more than I do. I also see people ship Phoenix apps without getting deep into that when their needs are relatively small.