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

Most of that is incorrect and revisionist history. The Web was developed on a commercial system (the NExT from Steve Job’s company) and initial implementations were made on various commercial systems by differing groups. Even today, Linux is at most 50% of the web servers on the Internet.