As agile gained popularity, for example with the popularity of scrum framework, people started to realize that it is not that simple to apply agile frameworks in a corporate world. One of the biggest problem was, of course, what to do with all the project and program managers.
That’s why god created scaled agile frameworks and the managers had jobs again.
But are such frameworks really agile frameworks as they tend to fix the content, the resources, and the schedule for a quite a reasonable time. It does not sound that agile – but it isn’t quite the text-book waterfall either.