What’s the single biggest advancement Linux has brought to the industry?
It’s an interesting question, and one that in my opinion has a very simple answer: Package management—or, more specifically, the ability to install and upgrade software over the network in a seamlessly integrated fashion—along with the distributed development model package management enabled.
It used to be that operating systems were big, monolithic products, and applications were big, monolithic products you put on top of them. If you wanted to deploy, say, a web application, you sourced the middleware stack (which itself was probably several big products too), you sourced the operating system, and you (often painfully) had to integrate the two yourself (or pay a big company lots of money to do it for you).