It’s not a pre built PC, it’s a gaming console that can also be a PC, if needed. That’s how the steam deck is marketed, that’s how the previous steamos PC was marketed, and clearly Lenovo thinks the marketing will work. A unified simple introduction to PC gaming as cheap as any console but with near infinite backwards compatibility is a pretty good sell to the normies who have nothing but marginal upgrades to look forward to in the console space.
… It’s a protocol, not a service. And your browser has it enabled. You can disable it on your browser and default back to esni, and be less private and less anonimized, if you want. No one’s making you use it.