I bought a book for a Japanese student who wants but is not able to read German texts. It was written almost 40 years ago. But it doesn't matter to me, for the German I must and have to read was also written around that period or even earlier. I don't need to know the latest German.
Books for novices in foreign languages written decades ago, including the one I bought today, appear to have been produced by earnest authors. That is, they know how demanding it is to learn a language and lead and help the readers to suffer the hardship, so that they will master it in the true sense of the word.
In contrast, today's books about foreign languages are naive and even hypocritical, for they pretend that the readers can learn a language without much effort or they try to relieve them of the burdens necessary to acquaint themselves with the language. No hardship, no commands of any language.
Where did the earnest teachers go? Their lessons can never be overestimated.