The Mass Relays blow up. They're gone. Let's ignore the fact that Mass Effect has already established that if one of these things blows up, it's effectively a supernova scale explosion that destroys an entire solar system. We'll go with what we see in the game and assume via some space magic that the pretty colored explosions are different somehow.
They're still -gone-. There are no more Mass Relays.
Which means that the entire vast armada you brought with you to fight the Reapers? They're stranded on Earth! Which would not have the resources to support that huge galactic armada if it was in it's prime! But now - no croplands, no infrastructure, no food, probably mass extinction of many native animals, and likely the beginnings of a nuclear winter style ice-age beginning due to all the dust and debris. So about a zillion people, several different species, (two of which can't even eat the native food anyway!) are stranded orbiting a burnt out cinder of a world with no resources, and no mass relays to go get resources.
So basically, in the BEST of all possible endings as presented, that entire vast armada that came with you to fight the Reapers? They're all going to starve and die. Woo victory over the Reapers. Yay. And now it's the Donner party scenario writ large on a galactic scale. Everyone's dead and screwed. That's just the reality of the situation.
And if there's no interstellar travel, what was the point of uniting the galaxy? Sure, the Krogans and the Turians have patched things up with each other. Too bad neither race will ever see the other ever again because they are in different parts of the galaxy. The Quarian Migrant Fleet? They got their homeworld back from the Geth. But now they can't get to it. And they'll starve and die in the Sol system. They're probably extinct. The Krogans and the Rachni are stranded here in the Sol system too. The Rachni are probably going to be extinct too after all of this. The Krogans back on the homeworld will survive. But the ones that came with you will starve with the rest. Assuming they don't go nuts and start killing people themselves.
So you went all around the galaxy and put all those conflicts to rest. Got people to cooperate with each other. To learn to live with each other. And for WHAT? They'll never see each other again! At least not in any of the current generation's lifetimes. And by the time they do, if they ever do, will it mean anything? WIll they remember?
So yeah. Invalidation. Pointlessness. Futility.
They're still -gone-. There are no more Mass Relays.
Which means that the entire vast armada you brought with you to fight the Reapers? They're stranded on Earth! Which would not have the resources to support that huge galactic armada if it was in it's prime! But now - no croplands, no infrastructure, no food, probably mass extinction of many native animals, and likely the beginnings of a nuclear winter style ice-age beginning due to all the dust and debris. So about a zillion people, several different species, (two of which can't even eat the native food anyway!) are stranded orbiting a burnt out cinder of a world with no resources, and no mass relays to go get resources.
So basically, in the BEST of all possible endings as presented, that entire vast armada that came with you to fight the Reapers? They're all going to starve and die. Woo victory over the Reapers. Yay. And now it's the Donner party scenario writ large on a galactic scale. Everyone's dead and screwed. That's just the reality of the situation.
And if there's no interstellar travel, what was the point of uniting the galaxy? Sure, the Krogans and the Turians have patched things up with each other. Too bad neither race will ever see the other ever again because they are in different parts of the galaxy. The Quarian Migrant Fleet? They got their homeworld back from the Geth. But now they can't get to it. And they'll starve and die in the Sol system. They're probably extinct. The Krogans and the Rachni are stranded here in the Sol system too. The Rachni are probably going to be extinct too after all of this. The Krogans back on the homeworld will survive. But the ones that came with you will starve with the rest. Assuming they don't go nuts and start killing people themselves.
So you went all around the galaxy and put all those conflicts to rest. Got people to cooperate with each other. To learn to live with each other. And for WHAT? They'll never see each other again! At least not in any of the current generation's lifetimes. And by the time they do, if they ever do, will it mean anything? WIll they remember?
So yeah. Invalidation. Pointlessness. Futility.