Having all the data in one place was not enough before LLMs.

Because you still needed a hyper-knowledgeable engineer to design and build any bit of functionality.

Swarming emergent functionality of finely enmeshed gears is way harder to accomplish.

All of the gears made by experts need to enmesh with all of the other gears precisely.

A coordination problem on top of the heavy lifting of engineering!

But now with LLMs if you get all of the data in one place and give just the barest of scaffolding, useful functionality can just emerge in place.