Except it is simple:
<html>
<head>
<title>Hello World</title>
</head>
<body>
Hello World
</body>
</html>
It's responsive, works on every HTML-compatible platform and is even backwards compatible to a degree that none of the other aforementioned solutions even comes close.
We make it more complicated for ourselves because we choose to make it more complicated. I'm not against modern frameworks but quite often I see people justifying them rather than using them when they become a requirement.
Worse yet, I'm often disappointed by the number of web developers I've worked along side recently that haven't understood how data is serialised in HTTP response and request headers (so they inappropriately use GET and POST methods), don't know even the basic few HTTP status codes, don't understand browser caching, etc and I end up having to handhold them through the basics while they're advocating complex frontend frameworks because "it does the logic for you" (or similar arguments).
This isn't a dig at all web developers by any means. I'm talking about a minority here. But it's a trend I've observed growing and I do think there is a correlation between the rise in popularity of bloated abstractions and the number of inexperienced developers using them as a crutch for their lack of understanding about the core principles of the web. The problem is the moment something misbehaves they're completely incapable of effectively problem solving it. And in the era of everything being a web browser, we have more low end devices than ever that we need to support - which often gets neglected when you have developers constantly opting for their shiny new toys resulting in cumulative page sizes of megabytes just to display "Hello World!".
So going back to my original point; yes I do think it can be simple to set up the kind of cross platform support you describe. I think it's often us who choose to make it complicated for ourselves. Often far more complicated than it ever needs to be.
