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 use

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.