Unfortunately, Firefox for iOS is built on Webkit, so there are no plugins for it, so this approach doesn't work on my iPad.

So far we can filter out some ads because for sites it's just cheaper to use off-the-shelf solutions from ad networks, which are the same for everyone, and to preserve accessibility via HTML. Enter heavy randomization or the canvas, and filters won't work. Look at Yandex: it took the fight with adblockers seriously, so uBlock's lists finally gave up—it just was no use.

If you try to use customization via CSS, on some modern sites the crazy mess of divs with cryptic classes already makes no sense and doesn't lend itself to CSS selectors.

My current anti-crap shield is a patchwork of various plugins/utilities, most of which only work on my desktop: a plugin to turn JavaScript off (this alone eliminates about 90% of the nonsense, while preserving most of the valuable content); a bookmarklet that hides fixed-position elements (wipes out a lot of the popups/reminders); and a plugin that lets me edit a site's CSS so I can manually remove the junk that the first two methods don't. (Using adblockers and readability plugins goes without saying.) A browser with all of those baked into it—especially, say, something like smart popup removal—would be something I'd be willing to pay for.

I don't believe the web is headed for death; not yet, anyway. There are certainly trends that are deeply troubling, but for most of us, building a website is still far more feasible than building an app.