Steam is not a publicly traded company, so they don’t pull this kind of skullduggery in service of the shareholders.
They’re a company full of people who, gasp, like video games: unlike the average navel gazing, brainless, Harvard Business School CEO.
Given their track record they’ve been more consistently “pro gamer” than other companies and are given a lot of leeway for that.
Here is a short list of things that Play Services do:
Even if you remove all telemetry you’d need to have the services running 24/7 in the background maintaining a socket connection to push notification services.