I think BI dashboards can work but only for very simple queries. If you are even at the point where you are asking non-technical people to execute joins on data I think you are in too deep and should just be writing SQL at that stage. Joins might seem very basic to some but honestly I find it difficult to wrap my head around them sometimes and with a UI like a dashboard which is less expressive than SQL I think it would just be a recipe for confusion.

It's ultimately a trade-off: you can make your tool more accessible to non-technical users than SQL, but it will necessarily be less powerful than SQL. And I still think there are plenty of use cases within that space. IME so much "BI" is just "I have two columns of data and I want to plot one against the other".

The author describes SQL as the only "self-serve" BI tool, but honestly, I think that is Excel. So many of these BI tools are just reinventing Excel with new (and therefore less familiar) interfaces. It is a meme to hate on Excel and I think that is because people have in the past tried to use it for complex stuff that really should be done in SQL. If we used SQL for complex data manipulation and Excel for "give me that as a pie chart", there would truly be no need for BI tools.