System images exist, but ok? Assuming most people don't have that technical knowledge, all those non-DRM games still work. I can copy and paste Kerbal Space Program and play it anywhere. The games with DRM I bought, I bought knowing what I was buying. I also bought knowing that what I was purchasing was smooth distribution and streamlined updates and safe and easy network play and not running random Russian .exes with an EDM soundtrack while cracking; but also with trust that those would still exist if Steam didn't.