I worked as a business intelligence analyst for a number of years where one of my primary duties was to perform not just 2 joins, but up to a dozen joins in order to collect data and format it into meaningful reports. Oracle has a number of great features that allow you to perform adhoc queries against million and billion-row tables very quickly. One such feature is materialized views which allows you to precompute dimensional summaries much like a MOLAP tool and store them in the database which can be access and just like a normal view. Another nifty Oracle feature is table partitioning which allows localized indexes and logic data grouping which cut query times down significantly. Analytic workspaces are another great Oracle DW feature which require more heavy lifting at the application layer.
Anyone claming that Oracle isn't a well-suited DW application obviously has little experience with the product or isn't using it correctly.