I hear that argument a lot, but it's not consistent with how we actually use "stealing". I think it's just a feel-good argument to justify that "no harm was done" with downloading a file illegally.
For example, we say that "he stole the answers to the exam" --in this case, too, the answers are still there, nobody lost them.
Here's what dictionary.com gives for steal:
1. to take (the property of another or others) without permission or right, especially secretly or by force: A pickpocket stole his watch.
2. to appropriate (ideas, credit, words, etc.) without right or acknowledgment.
3. to take, get, or win insidiously, surreptitiously, subtly, or by chance: He stole my girlfriend.
For example, we say that "he stole the answers to the exam" --in this case, too, the answers are still there, nobody lost them.
Here's what dictionary.com gives for steal:
1. to take (the property of another or others) without permission or right, especially secretly or by force: A pickpocket stole his watch. 2. to appropriate (ideas, credit, words, etc.) without right or acknowledgment. 3. to take, get, or win insidiously, surreptitiously, subtly, or by chance: He stole my girlfriend.