I am interested in this as well. Power BI is head and shoulders above anyone else in BI at the moment and I have never seen them make any deceitful claims. Every time it's "easy, but for advanced functionality you need DAX".
They are underselling it if anything, since it just punches so far beyond it's price point that most people who need entry-level BI would not understand how much of a good deal it is.
Self service means that you don't need to go through corporate IT, not that you need grand total of 0 dev skills. And even then, those tools abstract a lot of dev work. In the PowerBI case, DAX feels intuitive to anyone with Excel formulas experience. Other vendors have similar tooling.
