[CWuestefeld]

There's a kernel of truth here. But it's not true in the general case.

Others have responded about dynamic range and HDR, and that's one area where a particular feature set is necessary for certain kinds of photography.

Astrophotography and macrophotography both very nearly require focus-stacking abilities.

There's certainly a lot of photography you can do with just a camera, or with just a camera and very basic editing tools.

But having advanced tools opens up a whole world of possibilities. Those aren't all going to be things that everyone wants or needs to do. But there's a huge number of artists who will want or need some of them.