Many web developers make applications that are expected to work on every platform, every screen size, load instantly for new users, sync user state between every device instantly, and work offline (in some cases). All this takes place in an execution environment that perfectly sandboxes it, allowing users to download and run any application without any fear of viruses. Yes, the stack is complicated, but it's a complicated problem. The fact that people are making libraries to make web development simpler... well, no platform other than the web has even attempted to achieve everything I've listed, so we don't really have a point of comparison.