The Oracle Optimizer is continuously undergoing scrutiny and being tuned. In Oracle 10gR2 and version 11 some work has been done to improve the elimination of unneeded tables in joins. Although that might sound stupid to reference tables which are not required that is not as uncommon as you might think. Particularly in generated statements and views which select several tables, of which the user may only require data from one or two tables, this feature can have a great benefit.
The following article goes into more detail of how this feature can benefit your environment and what limitations exist.
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