It's related to a funny story that goes like this:
What if Bach had died before writing the WTK, then that music would not exist today, but all of us would be totally free to come up with it. Since Bach did live to write the WTK we don't have to wonder what it would be like if it did not exist.
Now what other stuff would he have done if he had lived even longer...
The problem with such thought experiments is that even though in theory we can come up with all the music that a composer would have written had they lived several hundred years longer in practice we probably will never do that because we are not that composer.
For art this is easy enough because we readily admit to an artist bringing something unique to the table, why else would an 'original' be worth a load of money (it's uniqueness being the direct consequence of the hand of the master). For scientific things that is a lot less clear.
I'm sure plenty of stuff will be invented anyway, no matter who comes up with it the first time. But that may not be true for all scientific ideas.