Yes but it is not really relevant for that book. OCaml has an incredible backward compatibility history, and the linked book is about learning the language itse

Yes but it is not really relevant for that book. OCaml has an incredible backward compatibility history, and the linked book is about learning the language itself, not its ecosystem. Things are different for RWO since it relies also on a number of extra tools and libraries which, indeed, change over time (sometimes also substantially)