The big shift has been from managing complexity to avoiding it where possible, encapsulating it when not. In my current favorite webstack, every logical view is abstracted behind an API (which happens to be a React Component). Internally, everything about that component is encapsulated -- the internal implementation, the sub-components, even the CSS thanks to CSS Modules. In fact, if I really had a reason to write a specific component in Angular or jQuery I would be able to: it's easy to embed non-React code inside React, and as long as it exposes a top-level React Component I'm hunky dory. I refer to React because that's my library of choice -- but you can say similar things about Angular and Aurelia.

This has only been something we've gotten right over the last few years. jQuery trampled all over the DOM, data-binding heavy frameworks like Backbone were impossible to reason about, Closure Library turned your Javascript into Java-flavored spaghetti, Coffeescript was basically Perl, and CSS was global by default. Now React lets me write perfectly performant abstractable code. Redux lets me manage state in a functional, reproducible way. Webpack supports CSS modules which let me write sane styles and code-splitting so I don't need to worry about managing resources. Typescript lets me write code that's safe and easy for others to consume. ES6 modules allow me to actually architect my codebase without shoving everything onto window. And the ringer is I'm not married to any of these technologies -- I can scalp out Redux for another data store, Typescript for Babel, go back to global CSS, etc.

Writing UI code is hard, and I'm not sure why some HN folks assume web developers are ignorant. Web apps are a HUGE hack, and it's funny to me that a forum dedicated to hackers has so many who shun it for that reason. It's not "flavor-of-the-month", it's finally making progress towards a really hard problem in really exciting ways.