I don't think the person you're responding to is "the Arduino type of hobbyist", though.

I feel the same, I didn't like Arduino's abstractions and how they hid what was actually going on. It has its appeals for people who don't care about the inner workings and just want to use a microcontroller to "quickly do something for which a microcontroller would be handy right now", but it won't get you much further than that, in my opinion.