There isn't any indication that the browser is ever going to be a competitor to standalone builds, and as a game developer I would never consider using an engine that immediately sacrifices the livelihood of my studio by precluding every platform I can make money on.
Games such as Battlefield have already used web technology to power much of the game chrome. Taking this a step further doesn't seem like a real constraint. Microsoft themselves are working to extend fast performance webviews to Xbox uwp's. https://github.com/MicrosoftEdge/WebView2Feedback/issues/215...
You're also not acknowledging the upside. Plenty of games would love to have an easy-to-make runs-anywhere multi-parryty game. Letting people log in from work or their phone could be a huge advantage to reaching markets. The market of people with access to web browsers is much bigger than the market of console owners!
You're also constraining your thinking to a narrow band in other ways, again ignoring plenty of great potential. Unreal has had huge success gaining entry into all kinds of unexpected spaces; cinema, architecture, events. Engines have a much wider market than just games, and having engines available on a much broader set of modalities than conventional game engines can unlock new use cases. No one's going to build a navigation tool requiring everyone to have a Steam Deck, but if all it takes is a phone then maybe that becomes interesting.
This also seems like an amazing starter kit for education and hobby coders. Wouldn't it be amazing to be able to be a year or two into learning development, and be able to create your own virtual world? That anyone can easily join & access from any device? That potential makes me thrilled.
Maybe this innovation isn't for you & you want to stick to conventional modalities. Fine, great! Don't use this. I for one see a lot of potential & reason for excitement. I think it has plenty of revenue potential, and vast amounts of cool potential.
That said, we do believe that the web _is_ changing, and that it's becoming more and more viable that one day we'll see big hit games actually played through the browser, for one simple reason; sending a link to someone where they can jump in and start playing with you immediately is a very powerful interaction (not having to wait for downloads etc.). And there are fundamental technological shifts that are making this more and more possible; WebGPU is opening up for more advanced graphics, WASM is making it possible to run near-native code, and WebTransport is making it possible to run more high-demand netcode in games. We're building Ambient on top of all those three, and while it's early days still, we're really excited to see what people can accomplish with them!