Understanding to Stale=false option in Couchbase Views

I am not able to understand, this paragraph in Couchbase documentation:

This means that using the durability requirements or observe feature to block for persistence in application code before issuing the stale=false query is no longer needed. It is recommended that you remove all such application level checks after upgrading.
Reference Link: https://docs.couchbase.com/server/6.0/learn/views/views-streaming.html

Complete paragraphs is below:

The stale=false view query argument has been enhanced. When an application sends a query that has the stale parameter set to false, the application receives all recent changes to the documents, including changes that haven’t yet been persisted to disk. It considers all document changes that have been received at the time the query was received. This means that using the durability requirements or observe feature to block for persistence in application code before issuing the stale=false query is no longer needed. It is recommended that you remove all such application level checks after upgrading.


It gives an indication to me that when Stale=false, in earlier versions, was used then only the data that was persisted on disk, was retrieved. But , i am not able to understand why in those cases, an application developer needed to apply some additional check in code.
In other words, the paragraph is not clearing the use-case due to which Sale=false has been enhanced.