Ah, GPL, the frontier license of Free Software movement. It was created by Richard Stallman to eradicate his greatest enemy – proprietary software. It promises to set you free from proprietary cages where software authors set restrictive limits on how their works can be used. With GPL there is no cage. You can go anywhere you want to go.
Except that there’s a line on a ground, that if you cross, flames burst from everywhere and lawyers jump out of nowhere swearing to destroy you if you don’t go back. The line is using GPLed pieces in something proprietary. You just aren’t allowed to do it.
This reminds me of words by Henry Ford:
People can have the Model T in any colour–so long as it’s black.
Ford hated colours other than black. Stallman hates proprietary software.
I have nothing against hatred, but saying that GPL is about freedom is hypocritical. By definition, freedom is ability to make choices. GPL takes the concept of open source and adds restrictions. So it’s not about freedom. Quite the opposite, in fact.