That said, your example of curing disease is a bad case of the broken window fallacy. No longer having to combat specific diseases 1) leaves people healthy and able to contribute to economic activity, and 2) leaves the people previously employed in medical fields able to take other jobs.
Maybe in 2016, where there's a seeming lack of jobs in the developed world, that's not a clear driver of economic growth, but in 1916, it was.
I suspect it's more likely that we're underestimating the consumer surplus from the internet than we are overestimating it. By how much, I don't know.
Or, to go back to technology, take Facebook for example. Perhaps people would have liked to have a social networking site before, but it simply wasn't available. When it became available, many people used it and enjoyed it in their leisure time. Because it's free, and, while large, does not pull very large revenues per user, it doesn't show up as a major economic activity. And because it's used mostly as an end-consumer leisure activity, it is missed by indicators that don't measure this well. So there can be a substantial total increase in services enjoyed, and we might be missing it. Again - might. I cannot say for sure, but it's worth asking.