I would probably do that if the time investment was worth it. For example if it was something I was using on a day to day basis but not for leisurely/exploratory reading.

Even for leisurely reading, you expect an author to still be updating a book several years after it was published? What experience has led you to believe that's a reasonable expectation?

I don’t “expect” the authors to do anything. But I am not going to spend many hours of my time reading a book when I see that the book is not maintained because there are many great books on my backlog that ARE being maintained by the authors/community.

All of my books are in pdf and receive zero maintenance - many of them are still incredibly useful.

I did not make a blank statement about the usefulness of outdated books. But certain topics do get out of date pretty quickly and would be less valuable to a maintained book.