[greggyb]

Except Microsoft's report editor, Power BI, includes a powerful columnstore database that can handle importing and rapidly aggregating 100Ms or even 1Bs of records with query response times of just a couple seconds.

That has been the differentiator. Power BI has lots going for and against it, but its database is miles ahead of competitors' report tools.

Edit: clarification: importing large volumes of data takes more than a few seconds. The query performance of the in-memory database after import is complete is what I referred to above in my original comment.