I'm actually pretty cynical when it comes to this kind of thing (for example, I don't think anyone can really compete with Google Search anymore), but I need to disagree with this article. It fundamentally misunderstands a few crucial elements of how game publishing (and consumption) works. Keep in mind that I am a long-time user of Steam (my account is 14 years old, having signed up literally the day it came out).
1. The gamers
Gamers are by definition quasi-technical and, by their very nature, will be welcome to (at least) trying out a new client or platform. I, and most of my friends, and probably most of Twitch, have not only Steam, but also GOG, and also the God-awful Origin, and Epic's launcher, etc. So installing a new client so I could play some games I like is really not that big of a deal. Steams social aspects were always secondary to its game delivery platform -- besides, most people use Discord to keep in touch, no one really takes Steam's "social network" seriously. I think that's a non-issue.
2. The developers
If you're an indie dev that's toiled for the past 3 years on a small game that you hope will make it big, you will release it on every platform -- let me say that again: you'll release on Steam, on Itch, etc. On every. Single. Platform. If you (really) want to sell AAA games, you can just be a run-of-the-mill distributor at first, and just sell keys. Worrying about developer friction I think is fundamentally misguided.
3. How to win
Imo, winning would look something like this: scout indie developers building the next big thing (they'll be a lot of false positives, so a lot of $$$ helps here). Make them sign contracts to only distribute through your platform. Do this for like 10 or 20 games, even if the contracts suck for you (hell, I'd give them > 100% revenue share). Now you're funneling people through your platform to play the newest "Cuphead" or "Super Meatboy" or "Dark Souls" -- obviously this isn't easy, but I do think you could hypothetically compete.and slow.