if you ever struggle to think of electronics and need to use examples always use water... it's far easier.

i.e. example 1 you have 1 hose pipe(outgoing signal) with a splitter in the end to make 2 outlets (2xsteppers)... water reaches the splitter and splits equally between the 2(both steppers get the same signal)

example 2 you have 2 hose pipes connected straight to 2 outlets and the flow of these is restricted by a computer, something goes wrong with the first outlet and the flow is slightly restricted at the wrong time compared to outlet 2.. you now have one pipe pouring more water than the other (one stepper moving out of sync to the other.

it's just limiting the possibilities of things going wrong. i understand what jazz is on about and i "go way back" with computers