Why is it so impossible to be honest about agile? Is it the religious overtones of having a manifesto that make it a belief structure rather then a development paradigm ?
"Agile allows us to create efficient metrics, openness and accountability." Really?
"Having red hair allows us to create efficient metrics, openness and accountability."
Well, it doesn't completely prevent us, but it certainly does not help us.
In a small outfit, where there is only one team and the task is basically mono-skilled then your agile teams can work as described but do not, IMHO, actually promote it. The real advantage of agile over waterfall is the frequent reality check of demoing to the end-user and the resulting feedback. This comes at the cost of not designing a solution before developing it.
Once the job requires more then one team, then the SM is the only channel of communication out of the team so your openness goes out the window. Metrics that only become meaningful when the team has done half a dozen sprints with no changes in skills, tasks and personnel are not, IMHO, exactly stable, useful or predictive. And 'accountability' that is based on an SM's ability to guilt less productive team members with no external checks or balances does not sound like the traditional ideal of productive teamwork.
Additionally, the active dis-incentive to up-skilling caused by metrics that punish activity that is not instantly productive and the lack of career progression caused by hiding talented people behind scrum masters does not encourage job-satisfaction or a willingness to go the extra mile. Agile has a place in software development, but it is not the be all and end all that it is often made out to be.