> Your only duty is to abide by the license.

We live in a society. I don’t see any harm in believing we ought to be respectful of the work. That’s all I’m saying. You don’t have to be, but it’s a better world if you are.

> If you want to enforce that everything built on top of a particular open source package also be open source, that belongs in the license.

Yes! I fully agree. The one that creates the thing is the one that gets to choose its license.

Having opened-sourced some bit of work myself, that’s a very difficult decision.