What else would these companies have to gain by making their games online only? Perhaps game developers even have contractual obligations to uphold, or incintives to include third party network interactions. The presence of Twitch, Cloudflare, and Microsoft on this list are interesting, because Microsoft drives a lot of threat intel and also makes a popular OS among gamers. If you want to reduce network traffic and reduce your reliance on third parties and internet access, migrating from Windows and using Proton on Linux would probably be a step in the right direction for many games that you would want to play single player.