With artboards you could toggle the grid while working within it, even with a child object selected. Now that we can build layout with frames within frames the shortcut will toggle a grid on the object I’m placing rather than the parent frame.
When working with grids I (very) often want to switch between visible and hidden. Typically I will place and resize an object with the grid on then turn off the grid to look at the design without the distraction of the gridlines.
I wish the toggle was on/off for all frames I have set a grid on, rather than per frame. I never really liked Sketch implementation of this toggle, and when I was teaching Sketch to begginers I saw many being confused (“You mean I have to select each layer to turn of the grids”).