So far, quantum computing is used in labs, not for any real useful purpose.
As far as I know - and we still had some tube radios at home when I grew up - they were used pretty much right away. For radios, and replacing mechanical relay switches, over which there obvious advantage was that since the tubes were not mechanical they would last longer, especially important in systems with lots of them.
So I'm not completely sure and somebody with definite knowledge should chime in, but I think they were not some "we have no idea what to do with this" but where useful from early on, as soon as the manufacturing method was solid. They were used for "normal" electronics well before they were used for the early computers. Even though Google search - which I just tried - also seems to have a bias and mostly associate those vacuum tubes with computers and forget all about the many other uses. It was the predecessor of diodes and transistors in addition to being better than mechanical relays.
https://www.engineering.com/story/vacuum-tubes-the-world-bef...
https://www.nps.gov/features/safr/feat0001/virtualships/vrmo...
(just one of the earliest commercial use cases as example for how short the period was between invention and wide-spread use)
> Dr. Lee deForest invented the vacuum tube in 1906. His tube, which he called the "audion," was first developed as a detector of radio waves and was quickly adopted by shipboard operators. Later experimentation, by deForest and others, showed the ability of the vacuum tube to generate radio signals with far greater precision than earlier systems. By 1914 the essentials of tube-based transmitters had been worked out.
https://en.wikipedia.org/wiki/History_of_radio#The_first_vac...
Radio existed (as you say) before the tube, but it took time to get the tube into real-world use. I guess this is somewhat like computing ; computing has existed in many forms, mechanical through to IC designs we have now.
But quantum? It's in a lab, and real-world applications are being worked out.
Paralleling back to radio again, people knew tubes would be useful, but it took 20+ years to make them mass producible, and make tubes usable, and redesign radios to use them. This, to me, sounds like quantum computing.
We can think of things I suppose to use them for (perhaps I was hasty on this point in my prior post), but we aren't there yet. And really, looking at the tube -- did anyone think they'd be used to make massive computers even?
I bet quantum computing will be the same way -- uses we're not aware of now.
