Scrum does not say “only focus on output”, but, unfortunately, humans will optimize for what they measure.
If you worry about story points & hitting your estimations, that’s what is going to consume your attention. That is what you and your team will optimize for.
And that is the core critique of Scrum as it is practiced: That it focuses a product team’s attention so heavily on delivery — on building lots of features quickly & efficiently — that teams fail to focus on spending time to discover what the right thing to build is.
The Scrum process says to break down stories into tasks to make estimation easier, encourage collaboration and to be able to show more granular progress during a sprint.
But after a few sprints, we decided to do the next sprint without creating tasks. As a result we drastically increased our velocity and never went back. Here I'll jot down some of the reasons we decided to do this:
Breaking down stories into tasks is time consuming
The tasks we came up with invariably would change as we worked on the stories
Tasks are repetitive
Tasks were often carried out in parallel
Our estimates didn't improve
It decluttered our task board
It encouraged collaboration throughout the sprint
While we started our process by following Scrum to the letter, we soon realised that breaking down stories into tasks was something that wasn’t worthwhile for us. In the end we realised that it was overplanning and poor use of our time. In the end we used that time to get on with the work and deliver at a significantly faster pace.