I think that this is intentional: tutorial gives some very basic ideas about what can be raised. Giving the whole context (you can `raise` two kinds of errors: `Exception` and `BaseException`, but they are different, should be used in different cases, and they are caught differently). Probably most users don't need to subclass `BaseException` at all.

And if they need to: there are docs for that https://docs.python.org/3/library/exceptions.html#BaseException

In my opinion - nothing should be changed there :)