This has certainly been asked for by players a number of times. I'm sure many would like it. IMO it's not nearly so appealing from the points of view of VR and Steam though. And both companies would have to put resources into making it happen.
Back when EA first opened, VR looked into being able to link VR-Pledged accounts to Steam. They agreed that it would be nice to do if it was possible. But they soon discovered that Steam would have to issue a game key to every VR account that wanted to log in thru them. And that Steam has some kind of technical limit to the number of game keys their system can issue for Pantheon subs. So every Pledge account allowed to link to Steam would be one less subscription that Steam could sell.
Hard to imagine Steam doing that for free. Even harder to imagine VR paying Steam any amount for those keys just to give them to us.
But even if that could be avoided, some not-insignificant amount of work would be needed to code in these new options to both VR's systems and Steam's. While it might be less work for VR, they are a small company with limited resources, and coding has been a specific bottleneck in development for some time.
For Steam, it would be even more work since players would expect to have all of Steam's social 'perks' that normally go with gaming through the Steam portal. So multiple systems (logins, tracking game stats, ingame communications, whatever else you get on Steam) would need modifying (and testing & debugging). The cost to Steam of making these arrangements, plus whatever increased operating cost they may incur, might not be such a big hit for Steam but would not (in the current arrangements that we know of ) bring in ANY additional revenue for them as far as I can see. Goodwill, sure. But no assured payoff they can count on.
Again, just not something Steam seems likely to agree to presently. Maybe down the road when Panth gets close to Release, if VR & Steam work out a long term deal then something like this could be included then.
While I appreciate you taking the time to respond. I don't feel like your take is quite the reality that companies deal with when publishing through Steam. If Embers Adrift could pull it off with 4 people on staff and extremely limited income, I don't think there is reason to speculate on whether or not it is possible and what long term relationships and contracts need to be drafted. This wouldn't be Steams first rodeo.