Without the gnu projects, software would have remained in the domain of universities and industry. Distributing it for free and encapsulating it with an actual legal license was radical in and of itself, but the notion of being required to distribute source was even more radical. Without that, people don't learn to code outside of industry, people don't share ideas and software remains in corporate silos with no/low interoptability unless a business decides to form a strategic partnership.

Without Stallman there wouldn't be GNU, so the operating system used to host this site and the majority of the web wouldn't exist. The compiler used to build that operating system wouldn't exist. The free software movement that later birthed its little cousin "open source" wouldn't exist, neither would the free culture movement to some extent. The ideals of the free software movement inspired the architects of the World Wide Web to make it a freely available technology, so without stallman the net would be vastly different, likely staying fragmented between different protocols like it used to be. Plus, the operating system you're using likely has some GNU stuff in it somewhere