Pizza dough with a mixture of strong and plain flour turned out surprisingly well. Lucky? Better with lower gluten?
As you probably know, various flours contain varying amounts of protein.  When water is added, and the proteins are hydrated, gliadin and glutenin combine to form gluten.  Gluten provides the structure and allows for stretch and rise. That is why a rest period after mixing is important.  You might find this informative. The folks at Serious Eats took a look at various flours and their impact on pizza crust. While flours with different percentages of protein all work, the end result is somewhat different, and mostly boils down to preference.  I make a lot of pizza. I usually mix and let rest for 24 hours before portioning, waiting a couple of more hours, then stretching and preparing the pizza. A long rest and a light touch are important to maintain a workable dough.  I mainly use Caputo type 00 flour, but have also used AP flour and combinations of flours.  In my experience "stretchiness" has more to do with hydration, time for the dough to relax, and a light touch.  Type of flour impacts flavor, rise, and texture.