A few things:

1. It gives manufacturers a blueprint for their devices. You will see a lot of handhelds running SteamOS from different manufacturers. You will also see a lot of small “gaming boxes” with SteamOS to plug in your TV. That’s great!
2. Game Developers will have one distribution to test their games on. One of the bigger problems linux had before SteamOS was the big clusterfuck of different distros. Great for users, but a big headache if you’re developing for it. Now you can say “it runs on SteamOS”, test on SteamOS and you don’t have to deal with bug reports from people running RedStarOS
3. It’s Valve. It’s a company. They are the biggest store selling games and they are building their moat to protect themselves against Microsoft, Apple, Epic & Co. That not exactly great for users, but also explains why Valve is doing this linux push. To prevent Microsoft from abusing their Windows monopoly to crush them

I would question your focus on growth. Yes, we all want this place to succeed. But do we really want this unlimited growth like Facebook, Reddit and all those other companies? Small communities are great, they give you a connection between users, they spark friendships and great discourse. Those are great. Yes, they are smaller than those multimillion user subreddits, but we’ve all seen those big subreddits slowly burning down. Dying to bots, to marketing spam, to low effort, popular comments, to reposts, to karma farming, to US politics. We’ve seen subreddit after subreddit dying to moderator burnout - because big subs are really hard to moderate, people will burn out. They are sacrificing their free time to deal with trolls, shills, putins guys and receive no compensation for that.

So maybe … let’s don’t replicate Reddit? Let’s focus on creating small, helpful communities and people will come.