Before software, a thing's representation and underlying mechanics were inseparable. It's weird to see producers greedy over their patterns now that it is (legally) possible to distinguish between the two..
Well, I'm guessing here -- but the first chair designer, when they distributed their chair, didn't include with their chair protective mechanisms to prevent users from viewing the chairs erognomics, or analyzing it with a microscope to understand its constituent parts.
Contrast this to DRM and substitute a decompiler or memory editor for a microscope.
Imagine a chair that you couldn't view but could sit in. That's what modern closed source software is, only the "you can't" is now legally enforceable thanks to the Internet.
For a while it was illegal in the US to "unlock" your phone: http://www.digitaltrends.com/mobile/unlocking-your-new-smart...