I now see that postgresql is the one true database. Everyone should abandon all other databases that don't have special features (ex: sqlite embedded).
I agree with you about PostgreSQL being late at adding these features, but SQL Server added CUBE and ROLLUP in 2008. They had GROUPING SETS longer, I think since 2000.
SSAS and other cube (MOLAP) tools create persistent cubes as materialized views. Databases that do ROLAP processing create "cubes on the fly" which persist for the duration of the query.
If PG adopts a materialized view that supports controlled automatic maintenance, then you'd have something similar to what the MOLAP tools do.
Note that MOLAP is a trap of sorts (no pun intended).
You could before. The benefit of OLAP databases and other analytical engines is only partly due to the focus of the query languages. Storage format, and calculation engine requirements are vastly different between OLTP and OLAP.
While the constructs in the linked article increase the expressive power of SQL, they are more icing than cake for an OLAP load.
I now see that postgresql is the one true database. Everyone should abandon all other databases that don't have special features (ex: sqlite embedded).