[1]: Linus Torvalds argues that the FSF tried to "sneak in" an additional clause to prohibit hardware locking. Since Linux was originally licensed with an "or later version" variant of GPL v2, that would've created a situation where Linus could not merge other people's work into the kernel without relicensing the upstream project to GPL v3. To prevent this, he later explicitly relicensed the kernel as GPLv2-only. https://youtu.be/PaKIZ7gJlRU