An interview with Linus Torvalds: Linux and Git

There's a fair number of these "dual license" projects where the original owner retains a commercial license ("you can use this in your proprietary product if you pay us license fees") and then on the other hand the project is also available under something like the GPL for open source cases.

And I think it's really hard to build a community around that kind of situation, because the open source side always knows it's "second class". Plus it leads to a lot of just licensing paperwork in order for the special party to always retain their special rights. So it adds a lot of friction to the project.

And on the other hand, I've seen a lot of BSD (or MIT or similar) licensed open source projects that just fragment when they become big enough to be commercially important, and the involved companies inevitably decide to turn their own parts proprietary.

So I think the GPLv2 is pretty much the perfect balance of "everybody works under the same rules", and still requires that people give back to the community ("tit-for-tat"). And everybody knows that all the other people involved are bound by the same rules, so it's all very equitable and fair.