While I hate always connected DRM, and lamented the death of physical media when steam got huge (and also refused to get a steam account for years for that reason), we would have multiple shitty stores if steam didn't exist, I think.
Look at epic and all the other distributors. Their stores are terrible and that's with the inherent competition of going against steam. Imagine if they were the only game in town. . .
Also looking at history. Download stores run by game stores. Or some startup. Some random extra DRM involved. Shut down in a few years without recourse... Just imagine that repeating every few years. Maybe fine for Linux and Mac users who expect no longevity from their purchases. But as PC user, no not acceptable.
Would the PC video game market be bigger or smaller without steam?