They also didn't define DTLB, ALU, or CPU for that matter.

I thought it was a good choice. They were assuming deep familiarity with modern CPU architectures through the whole text, so a one-sentence definition of all the terms would either have been too much, or not enough, depending on the reader.

It depends entirely on your audience. There is too much to define in these kinds of articles for it to be practical, it would way more than double the length, which is why it's better to just refer to a computer architecture course.