Being restricted to just using username () in measures (or AllowedRowsExpression) means that you cannot use the context of the current user in slicers or page level or report level filters. Just ...
Given that PowerBI is based on Analysis Services, could we ask for an implicit "Current User" dimension, perhaps with a single hierarchy "User Details", with two levels : 1: User Details (with a single member = the current user) and Attributes: User Name, User Principal Name, User Distinguished Name 2) Group Membership: (Multiple members, one per group the current user is a member of) and Attributes: Group Display Name, Group Distinguished Name PowerBI Desktop must be able to "inject" this dimension into every workbook, as it has knowledge of the desktop user, and if the workstation is part of a domain , it can query and populate the Group memberships PowerBI Services should also be able to create the equivalent, as it is AzureAD aware by definition. So "package" this concept into PowerBI, and make it available to users.
