GP is clearly talking about this is the same context that the GPL does. This is a decades-long running debate and it isn't as simple as you and the sibling commenters are trying to make it.
Of course it doesn't change the original project. But when people take the codebase and build a new product on it, what GP says is absolutely the case. The devs can withhold all code and rights to it from the next user. This is most commonly an issue when it comes to libraries rather than end products, but not always.
It doesn't also have to mean that the original project dies or disappears, it can just rob from their growth potential. Examples are quite easy to find. There's been a big hullaballoo over cloud providers taking open source projects and competing with them by offering managed versions of the service that are well-integrated into their ecosystems. Economically this is also a problem because the cloud provider can then undercut the price of the managed service compared to the official one since they aren't bearing the burden of building/maintaining the codebase.
I'm by no means against "permissive" licensing (MIT, etc), I think they have their time and place just like GPL, etc, but I am against dismissing valid concerns with shallow replies.
