Forum Discussion
Many to mAny relationship
The main reason is often people create these scenarios because they exist in the source system, so they blindly replicate the structures in the data modelling engine.
The primary purpose of a BI data model is to support reporting and analytics - and if you optimise your data structures for this scenario, you find you no longer need many-to-many relationships.
A purist would only use a relationship for filtering and not for cross-table calculations. Just don't be afraid of data duplication through multiple FACT tables :)
I didn't see it listed in the feature summary (https://powerbi.microsoft.com/en-us/blog/power-bi-desktop-july-2018-feature-summary/), but it looks like the "Many to Many" option (when creating a table join) is now available in the July update.