accumulation of increment - delivery before the sprint review
If an increment can be delivered at any time, wouldn't building up a backlog of increments to be delivered before the sprint review create clutter?
How important is a sprint review?
Multiple Increments can be created in a Sprint. The sum of increments is presented in the Sprint Review, thus supporting empiricism. However, an Increment can be delivered to stakeholders before the end of the Sprint. The Sprint Review should never be considered a milestone for unlocking value.
If an increment can be delivered at any time, wouldn't building up a backlog of increments to be delivered before the sprint review create clutter?
Why would increments end up in a backlog? If they are Done, wouldn't the imperative be to release them?
How important is a sprint review?
The Scrum Guide says: "Each event in Scrum is a formal opportunity to inspect and adapt Scrum artifacts". That event is not necessarily the only opportunity.
I don't quite understand what you mean by "building a backlog of increments to be delivered before the sprint review create clutter". What clutter? Where?
My understanding is that the phrasing around creating and delivering multiple Increments within a Sprint was to alleviate misconceptions around an incompatibility between Scrum and Continuous Deployment in software development. There were people who believed, incorrectly, that the Sprint was a delivery cadence and software could only be delivered once at the end of the Sprint. This phrasing clears up that misconception.
In any environment, if you deliver at multiple times in the Sprint, you review the cumulative set of changes or Increments delivered. In some cases, one of those Increments could have added functionality that was later modified or removed - telling this story and how it progresses the value of the product may be part of a useful conversation to have with stakeholders to explain progress toward the Product Goal.