Really? I think maybe you might be talking to quite a limited subset of photographers. Lots of landscape and architectural work is done fully manual for many reasons. Some of these are: 1) tilt-shift lenses are almost always manual only. 2) exposure/focus stacking. 3) panos. 4) long exposures with strong ND filters. 5) anything involving astro. 6) scenes with very large dynamic range.

There's a lot of other things too - your advice is really very over-simplistic and misses a whole lot of important things. There is no such thing as the perfect picture, artistic choices matter and there's more than one way to tell almost every story.