ETL is that which you develop custom systems by hand to..

-backup the truck and copy legacy systems data ( 20 different systems )
-marry the data together from different legacy systems ( compute farm )
-Compress the data by summarizing
-Do some transformations
-Load into Oracle using sql*loader Direct path you may get 1/4 billion rows loaded per hour
-transform the data some more using pl/sql and perl or java
-compress the data again
-roll fact tables up by dropping columns
-complete star schema
-optimize your partitioned world and make fast

Be told by snobby and stupid large companies you cannot work in their ETL department because you lack direct experience with...

Ab Initio
Informatica
etc.

GUIs that attempt to automate what you can do by manually and probably do better.