But they are not to be taken away from the team during a sprint! There is absolutely no recommendation to change the teams between sprints for the sake of chang

But they are not to be taken away from the team during a sprint! There is absolutely no recommendation to change the teams between sprints for the sake of changing either. The interchangeable part (although I have never heard it called that) is more that knowledge should be spread, so you don't end up with domain experts that end up "owning" part of the code.