@neethujkp
I think I can shed some light on this.
The reporting is based on envelopes send from the account and not signed envelopes. There is a sentence under the report to highlight this “on (your) sent envelopes”. As DocuSign Viewers cannot send envelopes, the reporting section is therefore empty and does not return any results.
Hiding the reporting sections for users with DS Viewer permissions may not have been done, as they might have had higher permissions before to send envelopes at one point. They would loose the functionality to report on those previously sent envelopes, if the tab would be conditionally hidden based on the permission profile.
Nevertheless this may be a worth an enhancement request to DocuSign. Please feel free to create a DocuSign Support ticket for it and share some more details on how you would image it should work in the future.