I blame designers/devs cargo-culting on fancy new stuff (webdevs on new css features, 2000s custom bitmapped UIs), and especially widescreen monitors on desktop, and pushing too much complexity to too small screen real estate on mobile as drivers of these processes.

Actually I found Windows Phone Metro UI as very well designed and clean UX for the small/touch-only screens, always showing a single view, but they backed out of that and made the current monstrous hybrids, with some worst of both words. (I was never really fond of the skeuomorph stuff on computers, and mobile UIs with lots of hidden interactions.)