Actually, it doesn't.ED does not have an end game mechanism because it does not end! The galaxy in ED is a living thing, your actions affect the way it lives.
Your actions have little to no impact on the galaxy. Sure you can swing who controls a system. But what does that change? Nothing!
The economy keeps on going, exactly as it was before. A system remains a democracy, might go into boom, might change its allegiance, but that has ZERO impact on the game itself.
You can kill thargoids as much as you want, a system with Goids will still get their system flipped to "damaged" on Thargoid-Thrusday.
You can sit there and watch a damaged station burn. The population never decreases. You can rescue 150 people, and you have the same amount of people on the station as you did before. Repeat 100 times, and you should have 15000 people less on the station.
An impact would be: You smuggle tons of nerve agents or uranium to a system to supply a group who then nukes a planet. There is impact.
That 700 tons of Titanium that you jetisoned in Supercruise while going at 20 times the speed of light impacted on a planet and had a devastating effect. (hole in planet, planet blew up, giant crater).
Someone crashed into a coriolis station and managed to stop it from spinning.
Your ship has a large mass. More mass means smaller objects gets moved aside. Why can't I move a 200t or 500t rock with my 1600t Anaconda? If my Thrusters are strong enough to move my ship loaded at 1600t, the asteroid should budge, yet it remains where it is, unfazed by a 1600t of a solid mass crashing into it.
If it'd be a living galaxy, you could make an impact. you could take 10 or 100 Anacondas and push Hutton Orbital closer to the Nav Buoy.
Changing who controls the system isn't really an impact.