I've never understood why "Hacker" News so frequently gets "But why though?" comments at the top.

The entire history of innovation is filled with people doing something just to see they can get it to work, even if badly, and then people continue to iterate on that until it works better, then works well, and then is so obvious people would never even question it. But it all starts with someone doing it to scratch an itch.

Neural networks, the foundation of our current AI revolution, used to fit well into the "neat, but practically useless" category.

Sure there are countless "but why though?" experiments that don't pan out, but that's just the cost of exploration. There can be no step-function innovation in a world where people only do things that make immediate practical sense.