I have no opinion as to whether the agents are "incorporated developer" or stabilizers in MGIV, but I definitely would call the image developed only in alkali more than "slight". It reaches quite a dark grey. For one of my normal negatives, in a typical 5x7 print, I need about 7 seconds of high contrast exposure to get max black in the rebate. This grey looks about like 4 or 5 seconds gives. This is on photo paper that has been fully exposed to room light.
But there has to be more to this story that I'm missing. I don't know what pH dektol is, but if I was getting the amount of development that I'm seeing with sodium carbonate in my normal split grade printing, it would be hard to judge the high contrast exposure needed -- and it's not. So the paper must not be developing that far only due to the pH of dektol.
BTW, I like MGIV and find it easy to work with. I don't know the correct lingo here, but when I'm judging a print and trying to get the contrast right, it works beautifully. Subjectively, I think the "whites are whiter and the blacks are blacker" and the steps in my test strips separate out beautifully. I'm new at printing and mostly use adorama brand because I'm learning and practicing, but when I use MGIV the process seems to go more easily and I like the results.
I didn't get to my tests this weekend ( a "new" fm2n arrived and I was developing a roll of FP4+ and making prints... which took up what photography time I had! ) but I haven't lost interest. I will add to my list of tests to put a normally exposed print into alkali and see what it looks like. I expect a print that will look flat and underexposed, but fully visible.