There's no doubt that Alain Briot has presented some good examples of color images that look more dramatic when converted to B&W.
However, what immediately struck me when reading his article and looking at the examples, is that many of the B&W versions compared, are different in content. The B&W images have not only been changed with regard to contrast, but improved with regard to the removal of extraneous stuff in the corners.
I get a sense this is not an objective comparison. An objective comparison would be to first process the color image, using selective contrast, brightness and color adjustments, to get the maximum, desired effect, before comparing it with the B&W conversion.
The fact that Alain has not even bothered to remove extraneous stuff in the corners of some of the color images used for comparison, greatly weakens his argument or thesis, and raises the question as to what other enhancements of the color images he has not bothered to implement before comparison.