as the article says these are GI wedges, and the though is to give for forgiveness into the wedges but by doing this and moving away from the blades you loose that shot shaping ability of the blades. The mindset behind it is i would guess is that players that need the GI wedges are not skilled enough to make those different type of shots with consistency or accuracy and thus would not have the need for that ability to be in their wedge.
I myself believe more in the combo set approach. That's more stated in the new Mizuno article where you get your GI in your long iron and progressively move into the blades for your wedges.
if you haven't read the article written by Tony Covey see below, it's a good one.
https://mygolfspy.com/2018-mizuno-mp-18-irons/