You can also publish games on Steam without DRM, as in, you can then just copy the game files and run them anywhere. Most don't because it's extra work and because it's hard to explain to your boss why you should untick that checkbox, while consumers who care mostly go to GOG anyway.
If Steam didn't have nominal DRM, I'd imagine they wouldn't have been able to grow to the point they're at now, and we'd instead have many stores each with their own exclusives, but most of them have worse terms than Steam. That world is worse than the one we have now.
And if you really care, there's always GOG, or the skull and crossbones.