It's not possible to do what you're describing (kanban/XP) for any commercial application or open source project that is intended to be taken remotely seriously without some amount of estimating involved.
I saw elsewhere that you're defining estimating as a very detailed and involved process, which the author of the article did not, the person I originally claimed estimates are impossible did not, and I did not.
I agree that's not necessary in most cases, if not all, to do the level of estimating you described.
And you'll note that I didn't include "people who are doing me a favor" in the list of individuals I'd insist on an estimate from.
You don't sound like you're one of these people, but I personally feel that software developers who act like they're performing special incantations over their keyboard and can't be expected to answer to anyone about their deliverables do us all a disservice, though maybe I should just be happy that they allow me to provide an alternative that is much easier to work with and results in additional business for me.
I am always fascinated when people tell me it is impossible to do something I have done. That plenty of people have done. For decades. But I shouldn't be surprised. Kuhn was not kidding around.
And yes, I strongly believe in accountability to business stakeholders, customers, and colleagues. I just think the better way is not paper fantasies, but demonstrated realities. Focusing on working software, customer collaboration, and responding to change, one might say. But people have said it before and it didn't make much difference.