The important point is that you can do that. If that actually is relevant in the end is another thing.

On the other hand if you don't have sources for the thing - you can just can't do it.

I think that's a rather important distinction, especially as probably everyone has been already hit by some project or service shutting down without being able to do anything about it. Especially in cases where you known you have the means (coding skills, computing resources to run the thing at least locally) to do something about it but you can't simply due to the source code not being available (you can take all the closed source components on the N900 & N9 as an example or a random proprietary API that is no longer available).