Power BI aggregations are meant to speed up queries to large DirectQuery tables, as a DBA would create summarized tables to speed up queries to large tables. The most appealing aspect of telling Power BI about these aggregations is that Power BI will automatically redirect the query to the aggregation cache if it determines that its dimensionality matches the dimensionality of the aggregated table, as explained in the documentation. However, there are a couple of limitations worth emphasizing that will prevent this from happening:
Click through for those limitations and what Teo & co did to move forward despite them.