Steam is a distribution platform, with DRM provided as an optional feature for the developer. If I wanted to play Deltarune without using the steam launcher, I can go to the downloaded directory and simply launch the executable. For convenience’s sake, most users will use the steam client to launch their games, and some games force you to due to developer choice. In order to play the game I wanted to play though (Deltarune), steam only served as a storefront and a download repository.