[nradov]

No that's not the correct way to do agile project management. As I have repeatedly pointed out, you can prevent most upstream / downstream iteration delays by organizing the project around feature teams, not component teams. But if you persist in using component teams for some reason then obviously both the producer and consumer teams must build in sufficient time into their story point estimates for iterating on the interface. As for defects that come up mid-sprint, either every team should keep a percentage of their capacity in reserve, or on larger projects you should dedicate a full Kanban team to maintenance.

Sure there are some managers out there who implement agile incorrectly by failing to follow best practices. But all of the problems you described are self-inflicted and easily avoided on agile projects with competent leadership.