I don't know if I agree... Ok, UI creation has gone down, but never the web had so much user created content. From tweets to videos and long texts it's easier to create content on mobile and in a much bigger volume than ever it was created.
"The medium is the message."
The possible shapes of a river are determined by the underlying landscape.
And sometimes rivers over flow and change the landscape, what's your point? The medium and message interact together and have pros and cons to different methodologies. Is painting a bad art form because the canvas is too restrictive to convey a message?