LLMs solve the biggest problem with language textbooks
Most languages have at least one high quality textbook written for secondary learners of the language. (This is no guarantee that one will be able to read the language that textbook is written in, but English to X is quite common, and some intrepid textbook writers have solved this problem by writing the textbook in the very language it is being taught in, starting with the simplest possible phrases and moving gradually up in difficulty.) ...