People did it, some times, when they needed it.

It was so rare that the GoF though they needed to write a book to teach people how to use those patterns when they eventually find them.

But after the book was published, those patterns became "advanced programming that is worth testing for in job interviews", and people started to code for their CVs. The same happened briefly with refactoring, and for much longer with unit tests and the other XP activities (like TDD).

At the same time, Java's popularity was exploding on enterprise software.