[TheLogothete]

You may, but that's not how the strategy guys at Microsoft see it, according to their own words. Data modeling and ETL capabilities rival SSAS and SSIS only in very trivial scenarios.

I'm not saying that to bash on PowerBI. I love that product and use it heavily and promote it to clients. It just serves different purposes than Tableau.

[greggyb]

The data modeling engine IS SSAS. The only major missing pieces are row-level security and defined KPIs. The query language, DAX, and the backing columnstore database are the same engine used in SSAS Tabular.

[TheLogothete]

xVelocity is only a (small) part of SSAS and it has a very limited application compared to OLAP even in the upcoming 2016 edition which greatly enhances the columnar store functionality.