What about GOG? Their client is optional, you can download full installers for offline archiving, no DRM.
First option that comes to mind that is clearly superior.
Steam's integrated multiplayer makes online games seamless, cloud save works better, the autopatcher beats offline installers anyday, its integrated Big Picture mode is great for TV or phone play, the built-in streaming works well, the built-in text and audio chat is useful, the Workshop allows seamless and fast mod installs vs having to use something like NexusMods, the reviews system is well implemented and waaaaay more informative than Amazon's, Proton is a godsend for Linux and the Deck, the built-in web browser overlay is handy for looking things up in the game, Family Share + offline mode is awesome despite having DRM, the sales are incredible (especially from 3rd party Steam resellers on isthereanydeal.com), the support is fast and human and very fair, GeForce Now integration is great when you're away from the gaming desktop, Valve is a gamer-centric and innovative company (Index, Deck, Controller, etc.)
And that's just for the player side. From the dev side the Steamworks API takes care of a lot of multiplayer and other stuff that normally is a huge PITA to reimplement.
As a client, it's just a MUCH better offering than either GOG or Epic or Microsoft or any of the other crap launchers. Like, not even in the same league... the others are just 90s-style download managers, while Steam is its own ecosystem. Despite not being a monopoly, they still continue to dominate the PC gaming landscape because they are just THAT good.
I had to re-buy Stardew Valley on Steam because the GoG version only had "connect to IP" (I cannot run GOG Galaxy on Linux) and all of my friends were using Steam versions that had other connect options.
But steam, for a 30% cut of a dev's income, will provide; Free save backups, free multiplayer and friends list management and apis, workshop support for modding, free keys to sell on other platforms or give away, a store that actually managed to reduce it's serious junk clutter problems for many people, VR runtime, HUGE controller apis that bring incredible functionality for remapping and macros, a system for game streaming and remote coop play, easy steam deck distribution now, a complete patch management and distribution system etc.
Basically Valve exposes a lot of features to game devs when you release on their storefront, and a huge amount of those features are just straight huge wins for gamers and consumers.