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"but Photoshop is another story, it is a tool for a different purpose which LR does not substitute yet."
Totally agree Lightroom is an alternative to Bridge / Adobe Camera Raw Plugin, it is not a alternative or substitute to Photoshop.
I have always said that the name of the product "Adobe Photoshop Lightroom" is misleading and confusing to new users.
There are other Adobe Products that are appropriately named, Adobe Illustrator, Adobe In Design etc.