The materialize hint forces the materialisation of a subquery result set into a temp table.
Generally it is not required.
Oracle will automatically materialize a subquery if it is referenced twice in an outer query.
If there is a benefit in using materialize when the CTE is only references once, then that suggests that the developer should be using no_merge.
In this situation, by using materialize, you are probably avoiding a detrimental query transformation arising from the view merging.
You might get similar benefit from using no_merge but without the small IO overhead writing/reading to/from the temp table.
More information is needed to confirm.
You'd need execution plan information with/without the hint.