Because as a GM, I prefer having direct control over the Edits. That way, I know for certain that any edit made was done with my knowledge and my approval, and it also means that if somebody goes inactive or withdraws but doesn't take down their Character Sheet, I can just remove it rather than jumping through the hoops of aving the Mods put it in "Inactive" spoilers and thereby making the thread look cluttered and messy. It also means that I can point to any unauthorised bios for the Mods and say "See? They posted it there without permission, so can you please get rid of it?" which makes my case stronger.
I get wanting to make your own edits, but as a GM, this way is neater and tidier for me, and makes a lot of complicated stuff easier.