Case in point: we got covid-19 vaccines so fast because the DNA sequence of the virus was posted for anyone to download by scientists working at ground zero. Much of the work was done before it was a global pandemic because of that sharing. Pair that with the work done on the mRNA vaccine for a previous coronavirus that didn't go far, and things weren't nearly as bad as they could have been.

This is a problem with trying to name One Most Important Thing. It's usually the synthesis of multiple innovations that makes the revolution.

Life expectancy at birth before medical breakthroughs (1900): ~41 years

Life expectancy at birth before the WWW started (1989): ~71 years

Life expectancy now: ~75 years

Source: https://ourworldindata.org/grapher/life-expectancy

I am thinking quite practical: do I prefer the internet over dying from smallpox or appendicitis, for example?

The added benefit of the internet for mass collaboration isn't that much in the data... why hasn't productivity exploded upward? Why hasn't medical progress gone through the roof? Scientist collaborated long before the internet. Quite strong progress was made without it.

I think your view has a distorted importance of medicine because you have never lived a live without it. And with that I mean felt the emotions of people going through it, like when your mother dies because of childbirth when you are a kid, your siblings die, because of infections.

Like we have today in all the anti-vaccination guys esp. in better-to-do households that are responsible for measles outbreaks even though it was deemed extinct. People from areas where it was common to have all these kids' diseases, we are not afraid of are much more pro vaccinations...

I can remember a time without the internet and while I really think it is great in many ways, humanity could do fine without it...