Because in my opinion the browsers would need to make it as easy to use as any other website or phone app if it were ever to gain traction.
Now, whether asking users to pay for a social network at all is a viable business model, is another question.
They could have all the same levels of security without the need to prevent competition.
I think a pattern where there are one or two great places at the lowest level of a Node program for program flow to act async, and then a bunch of business logic where it rarely is (probably running "under" the part where async makes sense, if you take my meaning) is far more common than those where async-friendly flow is what you want for over 50% of calls. "Call this chunk of code async, but run everything in it exactly in order" is super-common, and the interface to achieve that is exactly backwards in Node.
How?
It opens up the perfect opportunity for some competitor burning VC cash to swoop in and grab a ton of market share in a hurry, with a free iOS app.
FB knows this, so yeah, it's a completely hollow threat. But, just the idea that one of the tech giants has been backed into a corner by the risk of competition from paying-for-marketshare VCs or operating-in-the-red-on-purpose other tech giants, is really, really funny to me. No fun, eh Facebook? Hahahaha.
I don't get this popularity of async-await, especially in JS where I find its combination of syntax and absence of pre-run checks overly confusing and error-prone.
And this, seriously?
await $`exit 1`JS keeps coming up with new ways to make this less painful, but it's ridiculous every time because it's a fundamental problem with how Node presents itself. A comical sea of "await"s in front of damn near every call is the modern version of this, and is utterly typical in real JS codebases, but before it's been callback hell, or screwing around with promises all over your codebase when 90+% of the time you just wanted things to execute in order (from your perspective), and so on.
They could still try! But you'd have options.
Take email, for example. I cannot imagine something like that coming into existence today.
I can use my own client to avoid ads and tracking from my service provider—did I download this message? Sure, the server knows that. How long have I looked at the message? Which message did I look at next? Did I follow any links (yes, someone might track that part, but my email provider's going to have a hard time doing that)? What mouse movements did I make while looking at it? No such luck there, and yes websites and closed-platform services do track that stuff.
I can switch providers. Say my email provider starts injecting trackers into all links. I can just dump their ass if I don't like it. I keep using email, and now they receive zero info about me (I mean, they might get a little if I send emails to their users, but you get my point). If I have my own domain name I don't even need to tell anyone I switched.
I can email someone using a different provider. Yes blocklists or whatever might cause a problem but, fundamentally, this does work.
Protocols force providers to act like a telco, at least, except that the situation's even better for software because the barriers to entry in the market are so low... unless all your competitors are giving away access to their strictly closed ecosystem for free, and not supporting open protocols. Then you're screwed, and that's exactly what's happening now and why the Internet protocols are largely frozen in time.