
Such sites do not require a web server
Well, they do. It's just that you've separated out the bits that need a web server (an API) from the frontend of the application... which needs a web server to be, erm, served.
They can slate monolithic applications all they want. All these modern "solutions" that "decouple" everything and run on cloud infrastructure simply shift complexity elsewhere for no real benefit.
Give me a proper web framework and dedicated server any day over any of this hipster bullshit.