Blockades block the hyperlines, meaning one has to get through them to go...well anywhere, or get supplies, basically one controls the hyperlines, the planet is gonna be screwed cause they aren't gonna be getting a damn thing at any reasonable time.
Basically as Han put it in ANH, precise coordinates and all that noise, you gonna get all kinds of screwed over because hazards of space. Needing up to date info for your navicomputer constantly in order you don't end up as space dust.