> dramatically reduce complexity
If you ever worked seriously on anything non-SPA you would never, ever claim SPAs “dramatically reduce complexity”. The mountain of shit you have pull in to do anything is astronomical even by PHPs standards and I hate PHP. Those days were clean compared to what I have to endure with React and friends.
The API argument never sat well with me either. Having an API is orthogonal: you can have one or do not have one, you can have one and have a SSR app. In the AI age an API is the easy part anyway.