[noirscape]

...and that's why the Free Software Foundation requires signing CLAs[0], those evil commercial, proprietary product making rapscallions!

The reality is that without a CLA, copyright enforcement tends to turn into a complete mess. To be clear - that can absolutely be the point; a completely unenforceable copyright that's still enough of a mess to scare off violators can have it's uses; the Kernel jumps to mind. Linus and Greg have both been open about the fact that the license is there to encourage people to contribute as a carrot, not there as a stick to beat them over the head with. Explaining how the license works and why they'd really appreciate cooperation is much more useful for the LKML than it would be to keep a bunch of lawyers on standby and the fractured license helps achieve that goal.

They're often used by corporations to rugpull a license change, but the original purpose of a CLA is just to ensure that there's one entity in control of the licenses, which is more useful if an entity prefers the stick approach to compliance. (Which the FSF I would say absolutely lands under by-the-by.)

[0]: https://www.gnu.org/licenses/why-assign.en.html