David, thanks for sharing!
I feel the same about the double diamond being a siloed approach. Personally, I like to throw lean into the mix as well.
I believe by combining the agile, lean and design thinking mind sets and working collaboratively, teams can create the biggest value. Keep your customer in the middle of it and you should be golden. Of course, in real life, there are obstacles. But in a perfect world I’d imagine product development to look something like this:
Discover what the right problem to solve is, come up with ideas that help customer pains and/or add customer value, validate them through user testing/prototypes, build an MVP, collect data, learn from it and start over.
I am working on an article about this as we speak, so I won’t go into all the details now. But I foremost believe you need the whole team, the whole time. Working together as a team is a key part in this as well as being empowered by leadership to experiment and make decisions. This is a powerful combination, alas quite rare in the real world.