In Python 3, you don't care about what they use internally. You don't need to.
If you want to work with strings, you work with strings. If you want to work with bytes, you work with bytes. If you want to convert bytes into strings (maybe because it's user input that you want to work with), then you tell Python what encoding these bytes are in and you have it create a string for you. You don't care what Python uses internally, because their string API is correct and correctly works on characters.
That noël example of the original article consists of 4 characters in Python 3 which is exactly what you want.
I know that just using UTF-8 everywhere would be cool, but that's not how the world works for various reasons. One is that UTF-8 is a variable length encoding which has some performance issues for some operations (like getting the length of the string. Or finding the n-th character).
UTF-8 also isn't widely used by current operating systems (Mac OS and Windows use UCS-2). It's also not what's used by way too many legacy systems still around.
So as long as the data you work with likely isn't in UTF-8, the encoding and decoding steps will be needed if you want to be correct. Otherwise, you risk mixing strings in different encodings together which is an irrecoverable error (aside of using heuristics based on the language of the content).