Imagine you print loads of scores from IMSLP, drive you truck to Vienna and put up a big sign saying FREE SHEET MUSIC. Then people start coming.
- Do you have BWV 565?
- Can I have it?
- There you are.
- Do you have Bartok's Piano Concertos?
- Yes, but it would be illegal if I gave it to you.
- I don't care, can I have it anyways?
Now ask yourself: are you distributing copyrighted material? This is exactly what is happening now. The internet is only the distribution medium, so that you don't have to print the scores and drive your truck there.
Sounds like you love comparisons... will you appreciate this one:
Yesterday, I discovered that pushing the accelerator pedal of my car drives me easly to 110 mph. Unfortunately, in my country speed is limited to 80mph on the highways, and a police gave me a ticket. But in fact, I don't really care: I decided to use UE's argument and sue my car dealer. Obviously, by selling me a car that can reach 110mph in a country where speed is limited to 80mph he objectively favors speed limitation infringement.
Absurd, isn't it ?
In such a case, the car dealer is not responsible, because I took the decision to push on the pedal. As well, if I take the decision to click and download illegal material I my country, I'am the only responsible.