I'm curious what games you think superseded it within months of release? It came out in 1981 so I'd be curious what other 1981 games you think that are in the same genre that are better.

Steamworks is the mechanism under the covers that causes these games to require installing Steam.

When we had Impulse back in the day, we knew it was Steamworks more than Steam itself that was the key competitive advantage. But people forget that back then, multiplayer connectivity and the like was a significant hurdle for most game developers. Valve, more than anyone else, brought robust PC multiplayer to the mainstream. Requiring Steam to use Steamworks was very competitive at the time but given that Valve wasn't charging for it, it is also arguably a fair play.

But now, in 2021, there are plenty of other ways to do that so I'm a little skeptical to the argument that Steamworks is anti-competitive. You can easily make games now that feature multiplayer and other features that don't require Steamworks and thus don't require Steam to run.

The biggest advantage Steam has today is that it has a catalog of tends of thousands of games that already use Steamworks and are no longer being actively developed and thus they will only ever be on Steam. But there's no "cure" for that. It is what it is and new titles have plenty of options to get the features Steamworks has.

So even if you decoupled Steam (the store app) from Steamworks now it wouldn't make any difference because people go to where the games are and that's Steam.

What competitors of Steam need is money and time. Money for a steady stream of exclusives (or at least to use their Steamworks alternative which is decoupled from the store) and time for enough games to be released that aren't effectively Steam exclusives.

In short, the problem will solve itself imo.