Writers did agile before "agile"
When I hear debates on scrum and agile now, I think they were a solution to the fixed mindset problem.
The we know the future two years from now.
We know what customers want.
We know how to get them.
We know how to build it.
We assume what's "true" today will still be true 2 years from now.
It was the waterfall mindset of the last 50+ years.
But when I first learned it in 2013, I didn't have the history of how things used to be done. So when I listened to people who focused on the mindset, I understood.
And when I started branching out into other domains, I realized writers have been doing it since the beginning of time. They just don't call it "agile."