By “lack of developer freedom”, do you mean “lack of ability to take the freedom you got with the code away from the next person?”

Because that’s the primary restriction with the GPL.

So the only ones who could actually go after them to force anything are the ones who originally wrote that GPL code

Not necessarily, the SFC is involved in a big case regarding Vizio about this right now. The FSF was brought in to explain the intended interpretation and spirit of the GPL.