It does simplify things in places. One thing that isn't covered is that a code point is not necessarily a letter or vice versa. E.g. a single letter/symbol/emoji/whatever can be made up of multiple code points. So it isn't quite true that one "platonic" letter is one code point (it may or may not be).
You found a quality link.
If you deal with strings in Python 3 it kinda forces this distinction on you and I think is right to do so. It makes you painfully aware when you're assuming the world is utf-8.