Readability may go down for the lightened elements but the point I took is that you can actually increase contrast by recognizing it as a two-way street. I.e., de-emphasizing less important details is perhaps even more effective at making the main emphasis (in this case the relative heights of the bars) stand out than trying to highlight it directly.

Don't get me wrong--I agree that the units/what-are-we-actually-measuring, 'Calories per 100g', should be darker in the final graph (though I don't think it needed to be bold). I also think the direct-labelling step, which obviates the lightening of the y-axis and over-shoots attenuation in favor of full, bright whiteness is an improvement.

Lightening may not be the best independent step but I think it's at least illustrative as an intermediate one.

The idea is to keep focus on the data. The labels are reference when exact numbers are needed, but the data trend is king.