Sometimes I dock my pizza dough; sometimes I don't, but I've never had any sauce leak through any of the docking holes.
I have a large plastic/silicone roller with points that I use to dock my pizza dough and other pastries. Perhaps it doesn't "poke" as vigorously as a fork does.
I use this docker
http://www.amazon.com/Update-Intern...h+docker&pebp=1421288968257&peasin=B002NQIZOC
and I do 16" pizzas, so when I do a 24oz dough, I can dock it with no leakage, BUT if I do a thin crust and use my electric dough sheeter, say a 12 oz dough for 16" pizza with a good sized crust, you can almost see through that pizza, when I use the docker the pizza has sauce spots on the stone when I remove it..
So it all depends on the thickness and docker itself.. I HATE bubbles in my pizza, I like nice uniform flat pizzas, I dont like them big burnt cheeseless bubbles sticking out of the sauce. Plus who ever gets that slice gets a piece of burnt bread in the middle of their slice.
If I had a brick oven or super pizza oven built into my kitchen I probably wouldn't use screens, but with a std or convection unit sometimes its tough to get a nice dark bottom without over heating the top, with the screens you can get a nice bottom and not overcook the top and burn too much color into your cheese...
For the comment about the grille, I use a preheated stone for the grill, you get the opposite problem, the bottom is too dark and the top too light, I use a stone and the bottom is about as dark as the top when its done, with a tin pan the bottom is burnt so with a screen I am sure it will be worse...
I have done grilled pizza right on the grates, but I am not crazy about the results, the trick I learned for that is, get the grill super hot, bury the thermometer. Then put the pie on the grates, and turn the heat way down, close the lid and let it cook with the burner down low...