I agree with what your saying looking at it from a nutrient point by adding P. like I said before I think its in combination with a few other things
First off cannabis plants are light hogs, and everything starts with light. They'll take all light you can give them IF everything else is in balance with the light given , and the exact same is true for lower light intensity grows, their is a balance of 9 different things that, that balance is all determined by the light
From my point of view what I gathered over the last 25+ years , what i was taught by others and even through lab testing , I think most of your points are by products of light intensity and balance
speed is a by product of the growing environment, the higher light = more nutes, water oxygen co2 etc etc. And in turn I believe due to the high light intensity, faster more vigorous growing plants will product bigger , more resinous , and more completed flavor's, aromas oil's etc.
Here is where I think the P thing gets tricky , I don't believe this whole P thing is a stand alone trick so to say , In my testing with lab tests, extra p alone in low intensity grows is kinds useless, combined with temp / light there maybe some benefit in triggering pre-flower.
However in high intensity grows tests have shown that their is minimal deference in P uptake etc. I'm talking like 30ppm max difference in my solution, then when I trigger my environmental changes, its clear that there is a difference. Like I said before the faster my plant switches, the faster I get buds growing, the farther ahead I am come weeks 456 in flower, which in my opinion produce's a much better product. my plants don't get done any earlier.
I'd like to see what Dave says to I don't think P alone is a driving factor