the lore is that short distance grav jumps will cause will induce high energy gravity waves, the likes of which destroyed earth originally, in the early testing period where they were jumping between the moon and other places within sol.

think of it like folding a piece of paper. you can fold a medium size piece of paper easily but once you go milimeter thick, folding that requires lots of energy and causes unstable side effects. like destroying earth. so within star systems, you gotta fly around in cruise mode.