this is really true in my experience. I worked on a large server for a few years and most of my work was spent doing pretty mundane things (mostly interfacing with other libraries(apis)). I certainly didn't use every feature and, like you note, most programmers don't. Sometimes I would come across a new C++ capability that was utilized and I would just learn and utilize it, but this depended on the feature and situation. In fact, the only thing that's really different about it (at least to me), was the constant concern over memory usage (and all of the make/build stuff). These are just parts of the language that you need to consider that are avoided in other languages (the dirty secret here is that regardless of the language, you still need to consider them). I liked C/C++ because you can pretty much do anything with it, but you can get to certain points faster with a different language (again, depending on the target usage). Language platforms capture programmer inertia, which is why big companies try to own them. However, in reality, since there are so many, most good programmers seem to be able to switch between them fairly easily (which is a good thing).

When someone with a PhD in the relevant field, 6 or 7 years of professional programming experience and several successfully shipped products under his belt starts learning something new, he's a junior at that new thing.