Frontend, backend, workflow engines, payments, idk all of it.
Like you can make a cross-platform react native app with expo in a day without any AI (a proper app, not a boilerplate). Same with many web apps.
Shadcn with themes and components, tailwind, temporal workflows, etc etc. The complexity of making apps was solved years ago.
We must live in different worlds. Even for professionals building high quality apps is hard. It's easier with AI, but it's still quite hard. And it was definitely harder without AI.