I think you're misunderstanding my conjecture. My point is that there is no technical reason these features can't live on the web. I'm not talking about the incidental or intentional decision by some company to force user behavior by not providing a web solution.
Yes, theoretically anyone could build anything. Building it is not, nor was it ever the hard part.
There’s no financial, political, or mass market incentive for browser APIs to have feature parity with mobile OS APIs. Approximately nobody wants to do what you’re asking for. If anything, there are incentives against doing this.