> I don't really understand why the complexity of building websites is growing instead of going down.
People are doing things with websites they never did before. Office applictions, games, native-like UIs, real-time messaging, analytics and dashboarding, programming.
Good or bad, websites today have different interactions, behaviors, and development costs than 10 years ago. It sneaks up on you but if you see screenshots or use an old website you will immediately notice the difference.
> but while doing so we are creating hundreds of problems that never existed before.
Such is innovation.
> Tens of years of "evolution" and we just keep making everything slower and more complex for no reason, apart from being bored or wanting to be trendy.
Try making a website good enough that people will actually pay for it.
You may find your opinion changes.