[simne]

> but if you have any other contributors, those contributions are still under GPL.

You hit the bull eye.

These all projects as I could see, have relatively low number of important contributors and narrow circuit, and they are mostly relatively young projects, without large number of inherited old code, so when need to throw out some code, they just need to make internal deal and rewrite all "external" code.

Once, they have all code owned by limited group, could make deal within this group, to re-license whole project with other license.

And yes, you are right, this is near impossible for big projects, because need too much resources to rewrite "external" code.

And in many cases, for big business this mean, for them is easier to just make their own new project from scratch, than to use GPL-licensed code.