WebDev is as simple or complex as you want it to be. You can write clientside software in a single file that will run on almost any computer or phone in the world without needing the user to install anything. And you can guarantee that breaking changes to the language will never render your app unrunnable.

As apps' needs and the community of programmers gave grown, we have developed abstractions to make hard things easy. For example, you can build APIs in the language of your choice, often in a few lines of code. What is simpler than a Flask app?

Web development is way way simpler

No one is forcing you to pick up a full Angular 2.0+RxJs stack