Who will hold their breath? Who would invest in this? Software needs to be used by people. Software deliveries that cannot be estimated cannot be relied upon for planning. It may as well never be announced!
Now you understand sprints
And software that can't be estimated is still useful, even if you can't plan releases around it yet. "Apple has been unable to accurately estimate any release window for the Apple Car or Apple VR. Therefore no one should invest in it." would be a pretty silly statement, right?
That's exactly how it works though. Imagine Apple's stock price if they announce the Apple Car, without a release window. Now imagine that they come back the next day and say "oh by the way, we're aiming to release it in 2086." What happens to the price? It goes down. There was an implicit estimate used to judge the value of Apple.
Likewise, all software has an implicit estimate. There has to be! Without one, it's worthless.