When that source gets put in a product that is closed and then that product makes it to the user. How do people not understand this difference by now? Tivoization. It violates the four freedoms principle. That's how.
To quote zAy0LfpBZLC8mAC:
"A law that allows murder is more permissive and obviously does not increase freedom. It's simply a fallacy to think that not putting any limits on what any individual can do results in maximal freedom for society at large."